American Journal of Physiology-Heart and Circulatory Physiology

AimsGenome-wide association studies have identified numerous cardiac transcription factors in association with atrial fibrillation. Amongst these transcription factors, the paired-like homeodomain transcription factor 2 (PITX2) is the strongest genetic risk variant associated with atrial fibrillation. However, the downstream mechanisms of PITX2 are not completely understood. Here, we explore the role of PITX2 in oxidative metabolism and stress as a unifying mechanism of arrhythmogenesis. Methods and resultsTo identify PITX2 mechanisms, we performed transcriptomic analysis in Pitx2c-deficient neonatal rat atrial myocytes. We identify oxidative phosphorylation as the top dysregulated pathway and direct transcriptional targets lie in mitochondrial electron transport chain complexes I and IV. Using the Seahorse Extracellular Flux Analyzer, we identified a functional decrease in oxidative metabolism in Pitx2c-deficient cardiomyocytes. As electron transport chain complexes I and IV may generate reactive oxygen species (ROS) under mitochondrial dysfunction, we quantified mitochondrial specific ROS using MitoSOX and observed an increase in mitochondrial specific ROS in Pitx2c-deficient cardiomyocytes. We additionally assessed spontaneous cardiomyocyte calcium cycling using Fluo-8AM and observed an increased frequency of pro-arrhythmogenic mechanisms including early and delayed afterdepolarizations as inferred through calcium traces. Further, we identified sarcomere disassembly including a potential role of PITX2 in regulating Titin, where Pitx2c-deficient cardiomyocytes display Titin mis-localization within the sarcomeres. To assess whether ROS drives these phenotypes, we treated neonatal rat atrial myocytes with N-acetylcysteine, a potent ROS scavenger, and observed decreased early and delayed afterdepolarizations, as well as restoration of Titin localization. ConclusionPITX2C maintains atrial metabolism and redox balance; the loss of PITX2C results in reduced oxidative metabolism and an elevation in oxidative stress that ramifies cardiomyocyte dysfunction. Treatment with antioxidant restores AF-associated phenotypes including abnormal calcium cycling and sarcomere disassembly in Pitx2c-deficient atrial cardiomyocytes. TRANSLATIONAL PERSPECTIVEGenetic variants close to the PITX2 gene associate most strongly with atrial fibrillation. This study reveals a mechanistic link between multiple AF-associated phenotypes and mitochondrial dysfunction with subsequent accumulation of reactive oxygen species downstream of PITX2. Importantly, metabolic therapies and reducing oxidative stress may present a potential clinical strategy to reverse and prevent functional and structural remodelling related to AF.

BackgroundAntihypertensive and cardioprotective medications are prescribed to pregnant women and include Ca2+ channel blockers (CCBs; amlodipine, nifedipine), - (doxazosin) and {beta}-(labetalol, bisoprolol, nebivolol) adrenergic receptor antagonists, and -adrenergic receptor agonists (methyldopa). These vasoactive drugs enter the fetal circulation, with unknown effects on the fetoplacental vasculature. We aimed to investigate whether cardiovascular medications modulate human fetoplacental vascular tone, which may impair or enhance placental perfusion. MethodsChorionic plate arteries (CPAs) were obtained from the placentas of women with normotensive pregnancy (N=28), with unmedicated hypertension (N=14), and those chronically medicated (N=61) with either amlodipine, nifedipine, labetalol or bisoprolol, or a combination of CCBs and labetalol. Using wire myography, ex vivo effects of amlodipine, nifedipine, labetalol, methyldopa, doxazosin, bisoprolol and nebivolol were tested in a concentration-dependent manner (10-11-10-5M) in pre-constricted CPAs isolated from the placentas of normotensive women. Differences in CPA vascular reactivity in response to chronic exposure to hypertension and/or cardiovascular medications was assessed by vasoconstriction to high potassium physiological solution (KPSS; 120mM) and to the thromboxane A2 mimetic (U46619; 10-10-2x10-6M), and relaxation to the nitric oxide donor, sodium nitroprusside (SNP; 10-10-10-5M). ResultsIn pre-constricted CPAs isolated from normotensive women, acute exposure to amlodipine, nifedipine, doxazosin and nebivolol promoted significant vasorelaxation (P<0.05). CPAs acutely exposed to labetalol, methyldopa (P<0.05) and bisoprolol (P<0.001) exhibited increased vasoconstriction compared to their respective diluent controls. CPAs from women with chronic hypertension and from those who had chronic labetalol treatment exhibited significantly reduced vasoconstriction to KPSS (P<0.05). CPAs from women with chronic hypertension and exposure to bisoprolol also had significantly attenuated vascular responses to U46619 and SNP (P<0.01 and P<0.01, respectively), compared to normal pregnancy. ConclusionsMaternal hypertension impairs vascular responses of the placenta. Cardiovascular medications prescribed during pregnancy may dysregulate placental vascular function. Further research is warranted to evaluate the relative safety of cardiovascular medications in pregnancy, as their distinct effects on fetoplacental vascular function may have important implications for maternal and fetal outcomes. Mechanistic studies alongside clinical correlations are essential to guide evidence-based prescribing.

Pregnant women are particularly susceptible to adverse outcomes from environmental heat, yet the physiological effects of acute heat exposure during pregnancy remain poorly understood. Some physiological changes are monitored in humans; however, investigation of underlying molecular mechanisms requires invasive methods that can only be ethically applied in mammalian models. Moreover, research with animal models has largely focused on early and lethal teratogenic effects of heat exposure and lacks longitudinal physiological monitoring, detailed parameterisation of heating regimes and in-depth investigation of underlying mechanisms. Here we used a mouse model to investigate the impact of a controlled acute heat exposure at mid-gestation (E12{middle dot}5), slowly elevating core body temperature (CBT) over 210mins to raise CBT by [~]1{degrees}C. Using high-frequency ultrasound and morphological analyses, we observed delayed alterations in placental and foetal cerebral blood flow indicative of a brain-sparing response, alongside reduced placental labyrinth zone size. Additionally, maternal cardiac function was impaired, accompanied by cardiac and renal fibrosis and elevated circulating soluble Flt-1 levels, an anti-angiogenic biomarker of gestational hypertension. These findings demonstrate that brief heat stress at mid-gestation can induce lasting effects on placental function and maternal cardiovascular health in a mammalian model, highlighting potential risks for pregnancy outcomes under increasing global temperatures. Together this data suggests that an acute exposure to heat elevating core body temperature by 1{middle dot}2{degrees}C can induce a long-term impact on both placenta and maternal health in a mouse model. It will be important to understand the molecular changes which underpin the pathophysiology and whether this is translated to humans.

BackgroundCoronary autoregulation is the ability of the normal heart to maintain constant coronary blood flow (CBF) over a wide range of coronary driving pressures (CDP). Despite being vital for survival, the mechanism of coronary autoregulation is unknown. We hypothesized that GPR39, present in vascular smooth muscle cells, together with its endogenous agonist 15-hydroxyeicosatetraenoic acid (15-HETE) orchestrate coronary autoregulation. MethodsWe created coronary stenoses of varying degrees in open-chest, anesthetized dogs where we measured CBF and CDP. In a subset of animals, coronary venous blood was sampled for eicosanoid, adenosine, endothelin-1, polyunsaturated fatty acids, and prostaglandins levels. Stenoses were recreated during intravenous administration of VC108, a specific GPR39 antagonist and systemic, pulmonary, and coronary hemodynamics measured. ResultsGPR39 was identified in coronary arterioles by immunohistochemistry and in heart tissue by western blot. In-vivo, 15-HETE correlated linearly with CDP over the autoregulatory range (r2=0.47, p=0.0024). Apart from 6-keto PGF1 no other metabolite had any relation with CDP. Prior to administration of VC108, CBF did not change within the autoregulatory range. VC108 had no effect of systemic and pulmonary hemodynamics but increased CBF (p=0.02 versus vehicle) by decreasing coronary microvascular resistance (p=0.01 versus vehicle), indicating that GPR39 participates in control of normal coronary vascular tone. With VC108, coronary autoregulation was abolished and CBF became CDP dependent (r2=0.96, p=0.004). ConclusionGPR39 and its endogenous agonist 15-HETE together orchestrate coronary autoregulation when CDP is reduced. These novel findings provide a mechanism for coronary autoregulation and could direct pharmacological treatment of various coronary syndromes in humans.

Background: For decades, cardiovascular physiology has been built on the assumption that arterial baroreceptors adjust heart rate (HR) to maintain a defined blood pressure set point. We challenge this paradigm fundamentally. Blood pressure and heart rate both change substantially in response to physiological stress and neither returns reliably to a fixed baseline value. This raises the question of whether a higher-order variable, one that remains stable while blood pressure and heart rate reset freely might better represent a truly defended, set-point quantity. Hypothesis: We hypothesized that the coefficient of variation of the instantaneous baroreceptor gain (IBS CV), expressed as the change in R-R interval per unit change in systolic blood pressure (SBP), is invariant across different physiological challenges. If IBS CV is fixed, then HR and SBP must vary proportionally, maintaining a stable gain relationship even as each changes in magnitude. Methods: To test this hypothesis, we had healthy adult volunteers undergo either the cold pressor test or passive orthostatic challenge. HR, SBP, IBS, and the coefficients of variation (CV, i.e. standard deviation / mean value) of each were measured at baseline and during each stress perturbation. Results: During orthostatic challenge, HR rose significantly while SBP fell significantly. Classically, this HR rise is attributed to baroreflex compensation for falling pressure. However, the critical observation is that SBP was not restored to baseline. Instead, it remained substantially reduced while HR stayed persistently elevated and HR CV increased significantly. A system primarily defending a blood pressure set point should augment baroreflex gain and suppress pressure variability; instead mean IBS showed no significant change, SBP CV amplified more than threefold, and IBS CV was unchanged. During the cold pressor test, both HR and SBP rose simultaneously, which is inconsistent with a pressure-defending system that would have suppressed HR in response to the large rise in SBP. IBS CV was also stable across this perturbation while SBP CV amplified dramatically. Conclusion: These findings challenge the classical baroreceptor set-point model and suggest that IBS CV, not blood pressure, is the primary regulated cardiovascular variable. Furthermore, IBS CV is likely to prove to be a more sensitive marker than blood pressure or heart rate variability for risk stratification in patients with hypertension, heart failure, or autonomic insufficiency.

Abstract Background: Poor sleep quality is associated with increased cardiovascular risk, although its relationship with left ventricle (LV) structure is poorly understood and ethnic differences in the relationship between sleep and LV structure have not been studied. We investigated the association between poor sleep quality and LV structure in a tri-ethnic cohort. Methods: A total of 1284 participants were analysed from the Southall and Brent Revisited (SABRE) study (age=49.9{+/-} 6.2y; male 75.9%, Europeans (EU)=615, South Asians (SA)=457, African/African-Caribbean (AC)=212). A composite sleep quality score was calculated, and LV structure was measured using echocardiography. Associations between sleep quality and LV mass indexed to height1.7 (LVMi), relative wall thickness (RWT) and LV end-diastolic volume indexed to height1.7 (LVEDVi) were estimated using multivariable linear regression with adjustment for demographic and lifestyle factors across three models. Analyses were performed in the whole cohort and stratified by ethnicity. Results: Compared with those who reported very good sleep quality, participants with poorer sleep quality had higher LVMi (4.8 (95% CI 1.4; 8.2)g/(m1.7*unit sleep score); p=0.006). When stratifying by ethnicity, the association between sleep quality and LVMi was unconvincing in EU (1.9(-3.5, 7.3)g/(m1.7*unit sleep score); p=0.493), whereas poor sleep was associated with higher LVMi in AC and SA participants (9.1(1.3;16.8)g/(m1.7*unit sleep score); p=0.023 and 5.8(0.5;11.0)g/(m1.7*unit sleep score); p=0.031 respectively). Conclusions: Poor sleep quality is associated with higher LVMi in older African/African-Caribbeans and South Asians, but not in Europeans. This may contribute to cardiovascular risk. Keywords: sleep, left ventricle, hypertrophy, remodelling

Right ventricular failure (RVF) is a serious disease with a high mortality but no effective pharmacologic treatments. We reported RVF was reversed by chronic treatment with an 1A-adrenergic receptor (1A-AR) agonist. Recent studies suggest mitochondrial dysfunction contributes to RVF. Therefore, we investigated if reversal of RVF by chronic 1A-AR agonist treatment involved improved mitochondrial function. A mouse model of RVF caused by pulmonary artery constriction (PAC) for 2 wk was chronically treated for a further 2 wk. with a low dose of the 1A-AR agonist A61603 (10 ng/kg/day) or vehicle (no drug control). RV dysfunction was assessed from the fractional shortening of the RV outflow tract (RVOT FS). RVOT FS for sham controls (46.5 {+/-} 1.3 %, n = 9) was reduced 4 wk after PAC (27.6 {+/-} 1.5 %, n = 13, P < 0.0001), but was higher after PAC plus 2 wk A61603 treatment (34.5 {+/-} 0.6 %, n = 14, P < 0.001). RV myocardial respiration rate (O2 consumption) for sham controls (776 {+/-} 51 pM/s/mg, n = 9) was reduced 4 wk after PAC (493 {+/-} 28 pM/s/mg, n = 15, P <0.0001), but was higher after PAC plus 2 wk A61603 treatment (634 {+/-} 30 pM/s/mg, n = 11, P <0.05). RV myocardial ATP level for sham controls (3.3 {+/-} 0.1 mM, n = 10) was reduced 4 wk after PAC (1.9 {+/-} 0.1 mM, n = 6, P < 0.0001), but was higher after PAC plus 2 wk A61603 treatment (2.6 {+/-} 0.13 mM, n = 7, P < 0.01). In conclusion, reversal of RVF after chronic A61603 treatment involved reversal of mitochondrial dysfunction. Consistent with our previous studies, this study suggests that the 1A-AR is a therapeutic target to treat RVF. HighlightsRV failure is reported to involve mitochondrial dysfunction which might impair RV contraction by decreasing cardiomyocyte ATP level. Using the pulmonary artery constriction model of RV failure, we found that chronic treatment with an 1A-adrenergic receptor agonist increased RV myocardial respiration rate, increased RV myocardial ATP level, and increased RV function. These findings suggest that the 1A-adrenergic receptor is a therapeutic target for treating RV failure, and that the mechanism involves improved RV cardiomyocyte bioenergetic status.

Background: AI-enabled electrocardiographic age (AI-ECG age) is a digital biomarker of electrophysiological cardiac health. Although cardiovascular physiology exhibits circadian organization, the circadian behavior of AI-ECG age and its structural correlates have not been defined in AF-naive individuals. Objectives: To determine whether AI-ECG age exhibits reproducible circadian patterns and whether disruption of these patterns is associated with left atrial (LA) remodeling, a marker of atrial myopathy. Methods: Continuous single-lead wearable ECGs were analyzed from two independent prospective cohorts (S-Patch [ClinicalTrials.gov: NCT05119725, registered November 2021]; Memo Patch [ClinicalTrials.gov: NCT05355948, registered May 2022]). In AF-naive participants with 48 hours of data, AI-ECG age was estimated every 10 minutes. Unsupervised clustering was used to identify intrinsic circadian trajectories. For clinical interpretability, participants were classified using a day-night difference cutoff (Age 0.6 years) as Restorative (Age >0.6) or Disrupted (Age 0.6). We assessed phenotype reproducibility and examined associations with left atrial volume index (LAVI) using multivariable regression and meta-analysis. Results: Unsupervised learning consistently identified three circadian trajectory patterns across cohorts. Under the simplified binary classification, the Restorative phenotype was observed in approximately half of the participants (47.6-50.2%). Phenotype reproducibility was moderate (Cohen's 0.518; ICC=0.51-0.54) and was not fully explained by conventional heart rate variability measures. Among participants with echocardiography (n=122), the Disrupted phenotype was associated with higher LAVI (adjusted mean difference 6.09 mL/m2; 95% CI 1.46-10.72; p=0.010) and higher odds of severe LA enlargement (adjusted OR 4.17; 95% CI 1.58?10.99; p=0.004), with negligible heterogeneity (I2=0%). Conclusions: Wearable-derived AI-ECG age exhibits circadian patterns in AF-naive individuals, with unsupervised learning identifying distinct trajectories. Attenuation of a nocturnal decline the Disrupted phenotype is associated with left atrial enlargement, independent of conventional comorbidities and static AI-ECG age metrics. These findings suggest that circadian electrophysiological aging phenotyping may capture a dimension of atrial structural vulnerability not reflected by point-in-time assessments, and support prospective studies to evaluate its clinical utility.

BackgroundWingless/Int-1 (Wnts) proteins are canonical Frizzled receptor ligands. Recent evidence indicates that some Wnts, including Wnt9b and Wnt5a, bind to polycystin 1 (PKD1), a transmembrane protein which can couple to polycystin 2 (PKD2) to form a non-selective cation channel. The functional significance of Wnts binding to PKD1 is unclear. Here, we tested the hypothesis that Wnts act through PKD1/PKD2 channels on endothelial cells (ECs) to regulate arterial contractility and blood pressure and investigated the cellular source and secretory regulation of vasoactive Wnt proteins. MethodsA wide variety of approaches, including inducible EC-specific PKD1 and PKD2 knockout mice, reverse-transcription polymerase chain reaction, Western blotting, immunofluorescence, pressurized artery myography, blood pressure measurements, patch-clamp electrophysiology, in vivo and in vitro Wnt and nitric oxide assays, and Wnt secretion assays. ResultsIntravascular Wnt9b or Wnt5a administration stimulates an EC PKD1/PKD2-dependent dilation in pressurized resistance-size arteries. Wnt9b and Wnt5a are present in serum and plasma and intravenous infusion rapidly stimulates a blood pressure reduction which requires EC PKD1. Wnts stimulate a PKD1-dependent non-selective cation current in ECs which through Ca2+ signaling activates endothelial nitric oxide synthase (eNOS) and small conductance Ca2+-activated K+ channels to induce vasodilation. Wnt9b acts solely via PKD1/PKD2 channels, whereas Wnt5a stimulates signaling through PKD1/PKD2, Frizzled-7 (Fzd-7), Dishevelled and c-Jun N-terminal kinase (JNK). Intravascular flow stimulates angiotensin II type 1 (AT1) receptors, which through Gq/11 and Porcupine activate Wnt9b and Wnt5a secretion in ECs. Wnts secreted in response to flow activate PKD1/PKD2 signaling in ECs and contribute to flow-mediated vasodilation. ConclusionsIntravascular flow activates AT1 receptors, which through Gq/11 and Porcupine stimulate Wnt9b and Wnt5a secretion in ECs. Wnt9b activates PKD1/PKD2 channels whereas Wnt5a stimulates both PKD1/PKD2 and Fzd-7 in ECs to induce vasodilation. Wnts contribute to flow-mediated autocrine/paracrine dilation and reduce blood pressure. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=92 SRC="FIGDIR/small/712518v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@158bad1org.highwire.dtl.DTLVardef@5113eforg.highwire.dtl.DTLVardef@f3b94eorg.highwire.dtl.DTLVardef@10ab479_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundVentricular assist devices (VADs) are used as treatment for end-stage heart failure in children and adults. We previously demonstrated decreased mitochondrial function and changes in cardiolipin, a mitochondrial phospholipid, in explanted pediatric and adult failing hearts. In this study, we tested the hypothesis that VAD unloading of failing hearts leads to positive changes in myocardial cardiolipin in both pediatric and adult hearts. MethodsVentricular tissue was collected from the same patient at time of VAD implantation and at transplant. Ejection fraction (EF), left ventricular internal diameter at end-diastole (LVIDd) and brain natriuretic peptide (BNP) were assessed pre- and post-VAD. Cardiolipin species from paired VAD core and explants were quantified using liquid chromatography mass spectrometry. Mitochondrial respiration was measured in ventricular tissue pre- and post-VAD in paired pediatric samples using the Oroboros Oxygraph-2k. ResultsVAD support led to increased EF and decreased LVIDd and BNP. The predominant cardiolipin species in cardiac mitochondria, tetralinoleoylcardiolipin, was positively remodeled in pediatric post-VAD myocardium, while adult post-VAD myocardium demonstrated significantly increased total cardiolipin and decreased oxidized cardiolipin but did not demonstrate the tetralinoleoylcardiolipin remodeling seen in pediatric hearts. In pediatric patients, VAD support resulted in significant increases in Complex I+II activity, and a trend toward increases in Complex I activity. ConclusionOur data demonstrate age-related differences in VAD-associated cardiolipin remodeling and suggest that improved mitochondrial function in pediatric VAD-supported hearts could be related to increased tetralinoleoylcardiolipin.

Cerebral blood flow (CBF) control is essential for normal brain function and is disrupted in pathological conditions. Arterial diameters are tightly regulated to provide on demand increases in blood flow in regions of neuronal activity. Pericytes (PCs) exhibit robust myogenic tone and may also respond to neuronal activity to fine-tune local resistance and blood flow. Thus, mural control of microcirculatory resistance may extend beyond arteries and arterioles. Yet, PCs electrophysiology and contractility have not been thoroughly characterized, and this prohibits an integrated view of brain blood flow control. In this study, we develop a detailed mathematical model of mural cell electrophysiology, Ca2+ dynamics and biomechanics. The model is informed by electrophysiological data in smooth muscle cells (SMCs) or PCs and predictions are compared against pressure-induced responses in isolated arterioles and capillaries, respectively. Simulations recapitulate myogenic constrictions and examine differences in contractile dynamics as we move from arterioles to proximal and distal capillaries. In arteriole-to-capillary transitional (ACT) zone PCs, increased mechanosensitivity, more Ca2+ influx through non-selective cation (NSC) channels and/or a higher sensitivity of the contractile apparatus to Ca2+ can compensate for reduced L-type voltage-operated (VOCC) Ca2+ influx and allow for robust constrictions at the lower operating pressures of capillaries relative to the arterioles. A significant Ca2+ influx through NSC relative to VOCC, however, can decouple the PCs contractile apparatus from electrical signaling. Vasoactivity to chemomechanical stimuli along the arteriole to capillary axis is progressively driven by VOCC-independent Ca2+ influx and Ca2+ sensitization with slow kinetics. The proposed cell model can form the basis for detailed multiscale and multicellular models that will examine physiological function at a single vessel or vascular network levels and investigate CBF control in health and in disease. Key pointsO_LIA mural cell model of electrophysiology, calcium (Ca2+) dynamics and biomechanics is informed by data and adapted for modeling cerebral arteriole smooth muscle cells and capillary pericytes. C_LIO_LIIon channel activities are characterized by patch-clamp electrophysiology in isolated cerebral smooth muscle cell and pericytes, and capillary and arteriole electromechanical responses to transmural pressure changes are assessed using novel ex vivo preparations. C_LIO_LIMyogenic constrictions in arterioles can be reproduced by pressure-induced non-selective cation channel (NSC) activation that depolarizes the cell, opens L-type Ca2+ channels (VOCCs) and increases Ca2+ influx. C_LIO_LIRobust myogenic constrictions in arteriole-to-capillary transition (ACT) zone pericytes may reflect significant Ca2+ influx through NSC, increased mechanosensitivity, or higher sensitivity of the contractile apparatus to Ca2+, potentially compensating for reduced VOCC density relative to arteriolar smooth muscle. C_LIO_LIA significant contribution of NSC relative to VOCC in Ca2+ influx, can decouple the contractile apparatus from electrical signaling. C_LIO_LIThe model shows how gradients in ionic activities, mechanosensitivity and/or Ca2+ sensitivity can alter contractile phenotype and electromechanical coupling along the arteriole to capillary continuum. C_LIO_LIThe proposed model can form the basis for detailed multiscale and multicellular models that will investigate cerebral blood flow control in health and in disease. C_LI

BackgroundSex-related differences in cardiovascular disease suggest the presence of intrinsic vasoprotective mechanisms, with estrogen recognized as an important modulator of endothelial function. Building on existing evidence, the present study provides mechanistic insights into how estrogen and nitric oxide (NO) signaling regulate selective pathways of oxLDL uptake, mitochondrial dynamics, and inflammatory responses during early atherogenesis. MethodsWe combined an in vitro endothelial cell-macrophage co-culture model with in vivo studies in low-density lipoprotein receptor-knockout (LDLr-/-) mice to investigate the role of estrogen in early atherosclerotic processes. Human aortic endothelial cells (HAECs) were exposed to oxidized low-density lipoprotein (oxLDL) in the presence or absence of 17{beta}-estradiol (E2) and the nitric oxide (NO*) donor S-nitroso-N-acetylcysteine (SNAC). Key outcomes included oxLDL uptake, mitochondrial oxidative stress, mitochondrial dynamics, and inflammatory signaling. In vivo, male and female LDLr-/- mice were exposed to a short-term high-fat diet with or without SNAC treatment. Plasma lipid levels, blood pressure, aortic lesion formation, and cardiac remodeling were evaluated. ResultsE2 reduced oxLDL uptake and oxidative stress, effects recapitulated by SNAC; however, these responses involved distinct entry pathways, with E2 preferentially modulating lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) dependent uptake and SNAC targeting caveolae-associated mechanisms. In parallel, both E2 and SNAC reduced Scavenger Receptor Class B Type 1 (SR-B1) expression, suggesting an additional modulation on oxLDL transcytosis via this mechanism. Endothelial cells exposed to oxLDL exhibited altered mitochondrial regulatory proteins, including superoxide dismutase 2 (SOD-2), dynamin-related protein 1 (Drp-1), and optic atrophy protein 1 (OPA-1). Despite reducing oxidative stress, E2 increased the expression of adhesion molecules and enhanced monocyte adhesion in response to oxLDL exposure, particularly when combined with SNAC. Strikingly, E2 also modulated macrophage responses, increasing interleukin receptor antagonist (IL-1ra) expression and reducing GDF15, macrophage inhibitory factor (MIF), macrophage inflammatory protein 3 alfa (MIP-3), and matrix metalloproteinase 9 (MMP-9) levels, consistent with a less pro-inflammatory macrophage profile. In vivo, HFD increased plasma lipid levels and atherosclerotic lesion area in LDLr-/- mice, whereas SNAC partially attenuated these effects without affecting plasma lipid levels. In vivo, female LDLr-/- mice developed approximately 50% smaller aortic lesions than males, despite comparable or higher plasma lipid levels. A dyslipidemia led to increased blood pressure and a hypertensive phenotype in both males and females. SNAC treatment reduced lesion burden in both sexes and prevented diet-induced hypertension in females. ConclusionEstrogen limits early atherogenic injury by reducing endothelial uptake of oxLDL, preserving mitochondrial homeostasis, and modulating inflammatory signaling. Together, the E2 and NO pathways regulate early atherosclerosis through distinct yet complementary mechanisms, offering a potential framework for vascular-protective strategies.

General anesthetics enable invasive experimentation but can affect cardiovascular and respiratory physiology, biasing preclinical outcomes. We compared five anesthetic regimens in adult male Wistar rats, tribromoethanol (TBE, 250 mg/kg i.p.), chloral hydrate (CH, 400 mg/kg i.p.), ketamine-xylazine (KX, 80/10 mg/kg i.p.), thiopental (TP, 80 mg/kg i.p.), and isoflurane (ISO, 4% induction, 2% maintenance), to investigate integrated cardiorespiratory and biochemical markers. Femoral arterial catheterization allowed continuous blood pressure (BP) and derived heart rate (HR) recordings, while ventilation was assessed through pletysmography at baseline (awake), during induction, and recovery phases of anesthesia. Variability was evaluated in the time and frequency domains, including HR, systolic blood pressure (SBP), and spontaneous baroreflex sensitivity. In an independent cohort of rats, butyrylcholinesterase (BChE), CK-MB, cTnI, and LDH were measured. Baseline BP was unchanged by TBE and TP, whereas all anesthetics affected HR. Minute ventilation and breathing frequency were reduced with all agents, while tidal volume decreased with KX and TBE only. LDH and cTnI were unaffected, BChE was reduced by KX, TBE, and ISO, and CK-MB increased with CH and KX. Variability analysis showed that all anesthetics depressed pulse-interval and SBP variability and shifted spectral power toward higher frequencies, while baroreflex sensitivity and effectiveness were consistently reduced. During recovery, KX and TP restored most variability indices, whereas CH, TBE, and ISO showed persistent suppression. These findings highlight distinct profiles of cardiovascular depression and biomarker responses across anesthetics and underscore the importance of accounting for autonomic variability when selecting different anesthetics in experimental protocols. HighlightsO_LIFive anesthetic regimens were tested in rats. C_LIO_LIAll anesthetics reduced ventilation, and KX and TBE also reduced tidal volume. C_LIO_LICH and KX increased CKMB, while KX, TBE and ISO reduced BChE. C_LIO_LIAll anesthetics reduced blood pressure variability and baroreflex sensitivity. C_LIO_LIVariability recovered with TP and KX, whereas CH, TBE and ISO showed persistent suppression. C_LI

Background The postmenopausal period is associated with a more adverse cardiometabolic risk factor profile as well as unfavourable cardiac remodelling patterns. However, it remains unclear whether and how the associations between risk factors and cardiac remodelling differ before and after menopause and in the corresponding age groups in men. Methods We used cross-sectional data from the baseline examination of the population-based German National Cohort (NAKO, age range 19-74 years). Cardiovascular resonance imaging (CMR) was performed on 3T MRI, and morphofunctional data of both ventricles were derived from standard short-axis cine balanced steady-state free precession. Associations between cardiometabolic risk factors and cardiac parameters were evaluated using adjusted multivariable linear regression, stratified by menopausal status in women and age group (<50 / [&ge;]50 years) in men. Results The final sample comprised 20,152 participants (40% women; mean age 47{+/-}12 years) from the NAKO MRI subsample. Cardiometabolic risk factor profiles differed across the stratified groups, with higher systolic blood pressure and less favourable lipid profiles in older participants. Ventricular volumes declined and concentric remodelling increased with age in both sexes, with a steeper age-related pattern observed in women than in men. Higher BMI in women was associated with higher left ventricular concentricity index (LVCI) in postmenopausal than in premenopausal women (0.097 vs. 0.047; p for difference = 0.016). Associations between triglycerides and ventricular volumes were strongest in premenopausal women and significantly stronger than in men younger than 50 years (e.g., right ventricular end-diastolic volume (RVEDV): -0.173 vs. -0.064, p for difference < 0.001). Sleep problems were more strongly associated with cardiac parameters in men, with significant sex differences in older men compared with postmenopausal women (e.g. left ventricular end-diastolic volume (LVEDV): -0.105 vs. 0.043, p for difference = 0.023). Conclusions Less favourable cardiac remodelling observed in postmenopausal women appeared to be associated with a higher burden of cardiometabolic risk factors rather than stronger associations between these risk factors and cardiac structure. Several associations showed sex- and age-specific patterns, including Body Mass Index (BMI), triglyceride levels, and sleep problems. These findings highlight the importance of controlling cardiometabolic risk factors across adulthood, and raising awareness for sex-specific differences.

AimsThe development of a method for isolating mitochondria from a specific cell type within a given tissue, while preserving their structural and functional integrity to the greatest possible extent, remains an ongoing challenge. The aim of this study was to establish a protocol for the isolation of mitochondria from rodent cardiomyocytes, characterized by minimal contamination with other cell types and a high yield of mitochondrial fractions originating from distinct subcellular regions of cardiomyocytes. Methods and resultsIn the present study, cardiomyocytes from guinea pig and rat hearts were isolated using a standard enzymatic digestion protocol in a Langendorff heart perfusion system. Traditionally, the isolation of organelles, including mitochondria, from whole cardiac tissue as well as from cardiomyocytes has relied primarily on mechanical tissue homogenization These conventional approaches involve the localized application of high pressure to cells, which may potentially damage delicate organelles, particularly mitochondria. Moreover, such homogenization preferentially releases mitochondria located in the subsarcolemmal region of cardiomyocytes rather than representing the entire mitochondrial population. In our study, we employed an alternative approach based on the gentle mechanical disruption of cardiomyocytes by passing the cell suspension through selected cell strainers using a cell scraper. This strategy facilitated mild disruption of cellular structures, significantly increasing the yield of mitochondria released from interfibrillar regions while preserving mitochondrial functionality. Moreover, this method decrease probability of sample contamination with mitochondria from other cells, based on cell size differences. The effectiveness of this method was confirmed by transmission electron microscopy, and high-resolution respirometry, which revealed no evidence of outer mitochondrial membrane damage, as indicated by the lack of response to the addition of exogenous cytochrome c to the incubation chamber. Moreover, mitochondrial oxygen consumption increased by 7.39 {+/-} 1.25-fold following the addition of 100 {micro}M ADP, reflecting efficient ADP-stimulated respiration. Furthermore, fluorescence measurements were performed. to assess changes in the mitochondrial inner membrane potential ({Delta}{Psi}). The isolated mitochondria were also suitable for electrophysiological studies using the single-channel patch-clamp technique. Additionally, mitochondria isolated using the protocol developed in our laboratory exhibited a high capacity for transplantation into H9c2 cells. ConclusionIn summary, our mitochondrial isolation method is rapid, efficient, and yields functionally competent mitochondria. These preparations are suitable for a wide range of downstream applications, including patch-clamp electrophysiology, analyses of oxygen consumption under various pharmacological conditions, as well as mitochondrial transplantation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=162 HEIGHT=200 SRC="FIGDIR/small/716092v1_ufig1.gif" ALT="Figure 1"> View larger version (85K): org.highwire.dtl.DTLVardef@613495org.highwire.dtl.DTLVardef@1c34338org.highwire.dtl.DTLVardef@722900org.highwire.dtl.DTLVardef@e1f7a6_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundDeoxycorticosterone acetate (DOCA)-salt induces greater increases in blood pressure (BP) and a more pro-inflammatory T cell profile in males compared to females. T cells contribute to DOCA-salt hypertension, however, the mechanisms driving T cell activation remain unclear. The NLRP3 inflammasome has been implicated in DOCA hypertension in male mice. Little is known regarding NLRP3 in females. The goal of the current study was to test the hypothesis that NLRP3 contributes to greater increases in BP and renal inflammation with DOCA in males vs. females. MethodsRenal NLRP3 protein levels were measured in normotensive and hypertensive male and female subjects and in male and female Sprague Dawley uni-nephrectomized (UNX) control and DOCA-salt rats. Additional 11-wk-old Sprague Dawley rats were UNX and randomized to: 1) DOCA + vehicle or 2) DOCA + the NLRP3 inhibitor MCC950 (10 mg/kg/day in saline) from 11-14 wks of age. At 14-wks-of-age rats were euthanized, terminal plasma samples and remaining kidneys were collected for flow cytometric analysis of T cells. ResultsRenal NLRP3 levels were significantly greater in hypertensive males and females vs. normotensive controls. DOCA increased BP in both sexes, with greater elevations in males. MCC950 attenuated DOCA-induced increases in BP in male, but not female rats. MCC950 decreased circulating and renal CD4 and Th17 cells in both sexes, although the effect was greater in males. ConclusionDespite both males and females exhibiting an increase in NLRP3 in hypertension, NLRP3 contributes to BP elevations only in DOCA-salt males.

Aims: Explainable advanced electrocardiography (A-ECG) can be used to estimate heart age from the standard 12-lead ECG. A-ECG heart age gap (HAG) represents the difference between A-ECG heart age and chronological age. Increased A-ECG HAG is associated with cardiovascular outcomes and can be used to communicate risk. The aim was to investigate whether A-ECG heart age demonstrates acceptable within- and between-session reproducibility. Methods: Healthy adults (n=42, age 23+/-4 years, 52% male) attended up to two sessions ~14 days apart, with 36 participants completing both sessions. During each session, five standard resting 12-lead ECGs were obtained while lying in the supine position with unchanged electrode positions. A-ECG heart age was extracted using dedicated software. Within-session reproducibility was assessed using all five recorded ECGs with coefficient of variation (CV) and a two-way random effects intraclass correlation coefficient (ICC). Between-session reproducibility was assessed using the first recorded ECG of each session with a paired t-test, CV and ICC. A further analysis assessed the reproducibility of the parameters used in the A-ECG heart age regression model. Results: A-ECG heart age showed excellent within-session reproducibility in session one and two (both CV 5.8%, ICC 0.99). A-ECG heart age was slightly lower in session one than two (24.0+/-7.5 vs. 25.5+/-7.8 years, p=0.04) and showed good between-session reproducibility (CV 8.3%, ICC 0.84). All but one parameter used to estimate A-ECG heart age showed acceptable within- and between-session reproducibility (CV<10%). Conclusion: A-ECG heart age demonstrates excellent within-session reproducibility and good between-session reproducibility in healthy young adults.

BackgroundPreeclampsia, a maternal hypertensive syndrome affect fetal brain development and cerebral angiogenesis, with potential acute and long-term consequences. Underlying mechanisms of these brain vascular alterations are unknown. This study investigates the role of thrombospondin-1 (TSP-1), an antiangiogenic glycoprotein, as a key mediator of communication between the fetoplacental and fetal brain endothelium in the context of preeclampsia. MethodsConditioned media (CM) of human umbilical vein endothelial cells (HUVECs) from normal pregnancies (NP-CM) and preeclamptic pregnancies (PE-CM), were used to treat human (hCMEC/D3) and murine brain microvascular endothelial cells (BMECs). A proteomic analysis was performed in plasma of the umbilical cord of normal pregnancy and preeclampsia. TSP-1 was identify using proteomic analysis and confirmed by Western blot. PE-CM depleted of TSP-1, using immunoprecipitation, was used to evaluate protein-protein interaction with vascular endothelial growth factor (VEGF). Antibody-mediated blockage of TSP-1 was used to investigate antiangiogenic effect and pro-angiogenic signaling pathways in brain endothelial cells exposed to PE-CM. ResultsPE-CM significantly reduced angiogenesis, migration, and invasion of brain endothelial cells and altered cytoskeletal organization. These effects were accompanied by reduced VEGFR2 and AKT signaling, indicating impaired angiogenic pathways. Proteomic analysis of umbilical cord plasma revealed elevated TSP-1 levels in preeclampsia, which was confirmed by Western blotting. TSP-1 was also increased in PE-CM, and immunoprecipitation assays suggested a protein-protein interaction with VEGF. Antibody-mediated blockade of TSP-1 restored angiogenesis, as reflected by increased total tube length, and rescued VEGFR2 and AKT signaling in brain endothelial cells exposed to PE-CM. ConclusionTSP-1-mediated endothelium-endothelium communication between placenta-brain axis in offspring of mothers with preeclampsia. This communication mediated by TSP-1 may contribute to acute and long-lasting cerebrovascular dysfunction observed in infants exposed to preeclampsia.

Background | Angina with nonobstructive coronary arteries (ANOCA) is a heterogeneous condition encompassing distinct endotypes representing different underlying pathophysiological mechanisms. Endothelial dysfunction is considered a central hallmark of ANOCA. However, studying patient-derived endothelial cells (ECs) remains challenging due to the limited availability of disease-specific endothelial samples. We therefore aimed to assess the feasibility of isolating and culturing ECs from catheterization material obtained during routine coronary function testing in ANOCA patients. Methods | Catheterization material was collected from 79 ANOCA patients (84% female, age 58{+/-}10 years) undergoing coronary function testing. ECs were isolated, expanded and characterized using immunostaining, flow cytometry, gene expression profiling and functional assays. Results | EC isolation was successful in 43% of cases and resulted in 34 primary EC cultures that were expanded up to passage 10. Isolation success was independent of clinical or procedural characteristics. Isolated cells exhibited typical EC morphology and expressed EC markers confirmed by immunostaining, flow cytometry and gene expression analyses. EC marker gene expression remained largely stable over passages. However, stress- and defense-related gene expression programs increased over time, while proliferation-related processes decreased. Functional assays demonstrated that the coronary catheterization-derived ECs showed typical properties of wound healing, angiogenesis, activation responses upon stimuli and monocyte adhesion. Conclusions | This study demonstrates the feasibility of isolating and expanding ECs directly from catheterization material collected during routine coronary function testing in ANOCA patients. These patient-derived ECs retain characteristic endothelial features and functionality. This approach offers primary EC cultures to study the mechanisms underlying endothelial dysfunction in ANOCA.

Background Microvascular dysfunction is a key component of many cardiovascular (CV) diseases. Assessing the retinal microvasculature through retinal imaging may therefore provide a window into evaluating a range of CV diseases. This study sought to generate hypotheses regarding relationships between different retinal microvascular features (RVF) and measures of subclinical CV dysfunction derived from cardiovascular magnetic resonance (CMR) imaging. Methods 182 participants with type 2 diabetes enrolled in the UK Imaging Diabetes Study (UKIDS) with CMR image data were considered for inclusion in this cross-sectional study. Fifteen CMR measures of cardiac structure, function, tissue characterisation, adiposity, and aortic distensibility were derived. One-hundred-twenty-eight participants (70%) were found to have eligible retinal images. An artificial intelligence (AI)-enabled retinal imaging analysis tool (QUARTZ) quantified eight RVFs from each participant's retinal image: arteriolar and venular diameter, area, calibre uniformity, and tortuosity. Correlation analysis shortlisted RVF-CMR variable pairs for multivariable regression. Regression coefficients represent change per 1 standard deviation (SD) increase in RVF. Results Sixteen RVF-CMR regression pairs were shortlisted for regression, and five remained associated after adjustment for potential confounders. Per 1-SD increase in venular tortuosity was associated with a 0.5ms greater left ventricular (LV) T2 mean, 0.6% worsening in LV global longitudinal strain, and a 2 mL greater left atrial max volume. Per 1-SD increase in arteriolar calibre uniformity and retinal venular area were associated with 9ms lower LV T1 mean and 0.2x10-3mmHg-1 greater proximal descending aortic distensibility respectively. No significant associations were found between RVF and LV volumetric or functional measures, or adiposity. Conclusions In a diabetic cohort, we identified novel and biologically plausible associations between RVF and CMR measures of subclinical CV dysfunction. This provides new insight into the relationship between the retinal and systemic vascular beds and supports the potential role of retinal imaging in evaluating CV dysfunction prior to onset of overt disease.