Physiological Reports

Background Blood pressure (BP) regulation in individuals with sickle cell disease (SCD) is influenced by a complex interplay of genetic and physiological factors. While SCD has traditionally been associated with lower BP, there is an increased risk of hypertension. Emerging BP research suggests significant heterogeneity across genotypes, age groups, and sex. Objectives: This study investigated the longitudinal effects of population-level characteristics and continuous clinical and laboratory predictors on systolic (SBP) and diastolic blood pressure (DBP) in individuals with SCD, with emphasis on the interactions between baseline and predicted blood pressure slopes over time. Methods We retrospectively analyzed longitudinal data from a cohort of 2,739 patients with diverse SCD genotypes. Descriptive statistics were documented across sex, age range, genotype, health status and relative systemic hypertension risk categories (rHTN-risk). Linear mixed-effects models provided estimates of fixed- and random-effects of baseline BP and of time-related BP effects, respectively. Post-estimation margins provided contrasts of baseline-adjusted BP means and of pre-specified time effects on BP patterns. Results Males had significantly higher baseline SBP ({beta} = 6.64, p < 0.001) but lower baseline DBP ({beta} = -2.61, p < 0.001) compared with age-matched HbSS females. Baseline SBP was more unstable compared with baseline DBP and baseline DBP was more predictive of future BP trends than baseline SBP. Genotype was a consistent predictor of DBP (p < 0.05), but not of SBP. Similarly, we observed increased risks of relative diastolic hypertension across most genotypes, while the prevalence and magnitude of systolic hypertension was lower across all genotype compared with HbSS. Conclusions Blood pressure trajectories in SCD patients are not uniform and are significantly related to genotype, age group and sex over time. Baseline diastolic levels were less heterogenous and exhibited clear upward trajectories over time. These findings support the need for patient-specific BP surveillance in the care and management of SCD.

Objectives To examine the acute effects of a single bout of high-intensity interval training (HIIT) on fetal blood flow distribution during the third trimester of pregnancy. Methods Thirty-four healthy pregnant participants (mean age 31.6 years, standard deviation (SD) 4.1; gestational week 33.8 (SD 0.4) completed eight 30-second high-intensity cycling work-bouts interspersed with 2-minute rest periods. Fetal heart rate (FHR), maternal blood pressure, and Doppler-derived blood flow indices in the middle cerebral artery, umbilical artery and vein, and ductus venosus were assessed before and after exercise. We estimated fetal liver blood flow and the ratio of umbilical vein flow to ductus venosus. Maternal heart rate (HR) and FHR were recorded throughout exercise. Paired t-tests compared pre- and post-exercise values. Results No significant changes were observed in fetal blood flow indices or distribution following exercise. Average maternal HR and FHR during the work-bouts were 158 bpm (SD 16) and 152 bpm (SD 12), respectively. Following HIIT, maternal systolic blood pressure increased by 5 mmHg (95% CI 1 to 8, p=.014), maternal HR by 22 bpm (95% CI 15 to 28, p<.001), and FHR by 13 bpm (95% CI 10 to 17, p<.001). We recorded 16 instances of FHR above normal range during HIIT. Conclusion A single HIIT session in late pregnancy increased maternal blood pressure and HR and transiently elevated FHR but did not affect fetal blood flow indices or distribution. Brief episodes of fetal tachycardia were observed but appeared to be clinically insignificant. Future research should investigate the effects of repeated HIIT exposure during pregnancy.

cGMP evokes arteriolar vasorelaxation and is generated in smooth muscle by the soluble guanylyl cyclase (sGC) stimulated by endothelial NO. Phosphodiesterases (PDEs) degrade cGMP and may contribute in diameter regulation. We examined arteriolar cGMP levels in real-time in vivo upon NO and acetylcholine (ACh) and effects of PDE inhibition. Changes in cGMP were measured by FRET using the indicator protein cGi500. Arterioles in the cremaster muscle of anesthetized mice expressing cGi500 were exposed for imaging. They were stimulated with various NO donors (DEA/NO, SNP, SNAP) and ACh with or without PDE inhibition (non-specific: IBMX; PDE-5 specific: sildenafil). Furthermore, dilations induced by ACh and SNP were studied in sGC-deficient mice. DEA/NO and SNAP led to a fast, concentration-dependent rise of fluorescence ratio of cGi500 (by 4.0% at 10{micro}M), that declined on removal slowly. These ratio changes indicated cGMP increases as verified by inhibition of the sGC using ODQ. PDE inhibition increased cGMP levels slowly despite NO synthase inhibition. However, it did not amplify NO-induced ratio increases, but the decline after drug removal was decelerated. Interestingly, ACh did not modify cGMP levels and dilations were not impaired in sGC-deficient mice. FRET-based imaging allows reliable real-time assessment of arteriolar cGMP levels in vivo. PDE activity does not limit the amplitude, but the duration of cGMP signaling after stimulation. Furthermore, we conclude that ACh does not release endothelial NO in murine arterioles. Preliminary experiments demonstrate that simultaneous measurement of cGMP and diameter is feasible using mice with expression of cGi500 in smooth muscle cells.

Skeletal muscles secrete a variety of cytokines in response to inflammatory stimuli such as lipopolysaccharide (LPS); however, the contributions of resident macrophages or other non-muscle cells to the secretory responses are not well understood. To determine the potential impact of resident macrophages to inflammatory cytokine production, we tested the LPS responsiveness of isolated mouse soleus muscle when a critical toll receptor adapter protein (Myd88) was knocked down only in myeloid-derived cells within the muscle (e.g. resident macrophages). The phenotype is referred to as LyzMyd88-/- ; the litter mate controls were Myd88fl/fl. In solei from LyzMyd88-/- mice, cytokine secretory rates for interleukin-6 (IL-6) and keratinocyte-derived cytokine (KC, CXCL1) were significantly reduced to 56.3%, and 60.6% of control, respectively, over the first hour of LPS exposure. In the second hour, secretion of granulocyte colony stimulating factor (G-CSF), IL-6, KC(CXCL1) and monocyte chemoattractant protein-1 (MCP-1, CCL2) were greatly elevated by 5-10-fold in both phenotypes compared to the first hour. However, only MCP-1 secretion was decreased to 70.6% of control in the second hour. We also tested the secretory response to buffer containing 1% sterile mouse plasma because dilute plasma is known to amplify the responses of macrophages to LPS. Treatment with 1% plasma alone affected baseline measures of some cytokines but resulted in no further increases in secretion during either hour of exposure. However, small and gradual increases in secretory rates were observed for several cytokines over the study period, with or without plasma, with the largest responses seen in IL-6 and KC. Overall, the results are consistent with a significant early contribution of myeloid-derived, resident immune cells to the cytokine secretory responses of intact oxidative skeletal muscle. In addition, small quantities of plasma in the buffer have no independent stimulatory effects on cytokine secretion

ObjectivesThis study aimed to compare exercise-induced changes in serum and salivary concentrations of cardiac troponin-I (cTnI) in athletes during and after a marathon. MethodsThirty-six male runners were recruited. Eighteen participants in group 1 completed a marathon (42.195 km), while eighteen participants in group 2 did not undergo this exercise. Blood and saliva samples were collected at twelve different time points and then analyzed for cTnI using an immunoassay. ResultsBiphasic cTnI release into the circulation was observed during and after the marathon. Moreover, a similar pattern of biphasic cTnI elevation was found in saliva. In group 1, salivary and serum concentrations of cTnI first peaked after 60 min of exercise (0.67{+/-}0.08 ng/mL and 0.76{+/-}0.07 ng/mL), decreased slightly towards the end of the marathon (0.40{+/-}0.06 ng/mL and 0.46{+/-}0.06 ng/mL), and then reached a second, higher peak 4 h post-exercise (0.72{+/-}0.09 ng/mL and 0.82{+/-}0.09 ng/mL), returning to baseline by 48 h after marathon completion (0.16{+/-}0.04 ng/mL and 0.18{+/-}0.04 ng/mL). In group 2, there were no time-dependent changes in cTnI concentrations in both saliva and serum. Deming regression and Passing-Bablok regression demonstrated that there was proportional agreement between salivary and serum levels of cTnI in both groups at all twelve time points. The Bland-Altman method revealed that there was a negative differential bias but no proportional bias in the data. ConclusionsDocumenting a similar, biphasic pattern of cTnI elevations in saliva and serum during and after the marathon provides a reliable non-invasive alternative without requiring a blood draw.

BackgroundCalcitonin gene related peptide (CGRP) hyperpolarizes pulmonary arterial smooth muscle cells (SMCs) and endothelial cells (ECs) through PKA-dependent activation of KATP channels. CGRP can diminish the severity of pulmonary fibrosis (PF), however, the effects on vascular signaling were poorly defined. We hypothesized that hyperpolarization to CGRP would be augmented in a mouse model of PF. MethodsPF was induced in male and female C57BL/6 mice by intratracheal delivery of bleomycin (3 wk), with saline used as control (sham). Pulmonary arteries (PAs; 100-150 {micro}m diameter) were cannulated and pressurized to 16 cmH2O, and endothelial tubes were studied in complementary experiments to eliminate the influence of SMCs. Membrane potential (Vm) was recorded continuously using intracellular microelectrodes. Responses were also evaluated in isolated lungs preconstricted with U46619 ([~]10 mmHg). ResultsPF led to greater indices of PH in males vs. females. Isolated lungs and PAs from male PF mice had enhanced vasodilation and hyperpolarization of Vm to CGRP, although no effect was observed in females. The greater vasodilation and hyperpolarization of SMCs to CGRP in males persisted in endothelium-disrupted PAs and during treatment with L-NAME indicating that ECs are not required for greater responsiveness to CGRP. With no effect on resting Vm, inhibition of KATP channels or PKA significantly attenuated hyperpolarization of SMCs and ECs, attenuated vasodilation to CGRP in PAs, and eliminated differences between groups in males. Direct activation of PKA, but not KATP, evoked greater Vm hyperpolarization and vasodilation in PF vs. sham PAs and lungs. Although no difference in sensory nerves was observed in fibrotic mice, perivascular nerve stimulation evoked greater vasodilation in PAs. ConclusionsIn a mouse model of PF, CGRP-dependent hyperpolarization of pulmonary arterial SMCs and ECs is augmented through increased PKA-dependent activation of KATP channels leading to increased vasodilator sensitivity.

After myocardial infarction (MI), pathological autonomic remodeling, including vagal dysfunction and sympathoexcitation, occurs and predisposes to ventricular arrhythmias (VT/VF). The underlying factors that drive this remodeling, including the observed neuroinflammation and glial activation, remain unknown. We hypothesized that sympathetic nociceptive afferents underlie this remodeling post-MI. Epidural resiniferatoxin (RTX, to ablate sympathetic cardiac afferent neurons) vs. saline was administered in pigs prior to MI and autonomic and electrophysiological effects assessed four to six weeks post-infarction. Acute effects of afferent ablation after chronic MI were also assessed in a separate group of animals. Baroreflex sensitivity and vagal tone, as measured by parasympathetic neuronal activity and cardiac nociceptive responses, were improved in infarcted animals which received epidural RTX prior to MI. These animals also demonstrated reduced spinal cord inflammation and glial activation, downregulation of circulating stress and inflammatory pathways, and stabilization of electrophysiological parameters, with reduced VT/VF-inducibility. Epidural RTX after chronic MI also acutely restored vagal function and decreased VT/VF. These data suggest that cardiac spinal nociceptive afferents directly contribute to VT/VF susceptibility and MI-induced autonomic remodeling, including oxidative stress, inflammation, glial activation, and reduced vagal function, providing novel insights into the causal role of these afferents in driving sympathovagal imbalance after MI.

Background Ischemic heart failure (IHF) has been shown to impair contractility and disrupt sarcomere function in the left ventricle. Left ventricular failure can cause left atrial dysfunction, which is associated with a greater risk of patient mortality. Despite this, the biochemical and biomechanical characteristics of the left atrium in IHF remain obscure. Methods Myocardial mechanical properties were measured using permeabilized muscle isolated from the left ventricle (LV) and left atrium (LA) of donors and patients with IHF. Tissue homogenates from these samples were used to measure titin and myosin isoforms as well as the phosphorylation of sarcomeric regulatory proteins. Histology was used to quantify fibrosis in the patients' left ventricle and left atrium. Results Length-dependent changes in Ca2+-sensitivity were blunted in LV myocardium from patients with IHF. LA myocardium did not show robust length-dependence of Ca2+-dependent force. The calcium sensitivity of both LA and LV myocardium was increased in IHF. The maximum force generated by LV but not LA myocardium was decreased in IHF. LA myocardial samples exhibited faster contractile kinetics than LV samples, irrespective of disease. Troponin I phosphorylation decreased in both chambers with IHF. Conclusions Left atrial IHF myocardium maintained contractile force and displayed increases in calcium sensitivity, which may allow for increased LA contraction under pathological conditions. The increases in calcium sensitivity observed in ischemic myocardium of both chambers are likely driven by decreased phosphorylation of troponin I, which alters thin filament regulation. Conversely, thick filament properties of the left ventricle, such as thick filament protein isoforms and phosphorylation of myosin binding protein-C, displayed chamber-specific differences independent of disease state. These biochemical changes may explain the chamber-specific differences in kinetics and length-dependent properties. Collectively, these biophysical and biochemical data suggest LA remodeling in IHF may assist in increasing LV end-diastolic volume to maintain adequate cardiac output.

Obesity is associated with an elevated risk of pathological cardiac hypertrophy, whereas exercise confers cardioprotective effects; however, the cellular mechanisms underlying these opposing influences remain incompletely defined, particularly in females. We investigated how obesity and exercise affect cardiomyocyte ultrastructure, Ca{superscript 2} release, and contractility in female Zucker Diabetic Fatty rats and their lean littermates. Animals were assigned at 12 weeks to sedentary or aerobic exercise-trained groups and maintained on a standard diet. By 18 weeks, obese rats exhibited increased body mass and myocardial hypertrophy in the absence of diabetes. Sedentary obese animals showed a reduced fraction of compact dyads and diminished stimulated and caffeine-induced Ca{superscript 2} release, while contractility remained preserved. In lean rats, exercise increased dyad density but reduced Ca{superscript 2} release, whereas in obese rats, exercise enhanced both dyad compactness and Ca{superscript 2} release. Across all groups, global cardiomyocyte ultrastructure and contractile function were similar. Type III ANOVA revealed a significant obesity x exercise interaction for dyadic structure and Ca{superscript 2} release. These findings demonstrate that obesity itself, independent of diabetes, triggers early dyadic remodeling and altered Ca{superscript 2} handling in female myocardium before detectable impairment of global cardiomyocyte structure or contractile function. Furthermore, exercise exerts beneficial effects on dyadic ultrastructure and Ca{superscript 2} signaling in obese animals. New & NoteworthyUsing a female rat model of obesity without diabetes, we demonstrate that obesity induces early remodeling of the dyadic system and impairs Ca{superscript 2} release in cardiac myocytes. We further show that the effects of aerobic exercise on dyadic structure and function are obesity-dependent, improving both dyad organization and Ca{superscript 2} signaling. These findings identify the dyadic microdomain as a vulnerable cellular site in obesity and a potential target for exercise-induced recovery.

Drug-induced inhibition of the delayed rectifier potassium (IKr) current predisposes to early afterdepolarisations (EADs) and cardiac arrhythmias. Here, we sought to determine the contribution of action potential duration (APD), APD variability and spontaneous calcium release from the sarcoplasmic reticulum (SR) in the formation of EADs. In isolated sheep ventricular myocytes, EADs were induced by combined inhibition of IKr with dofetilide and {beta}-adrenergic stimulation. The onset of EADs was preceded by increased beat-to-beat variability of APD. To isolate the role of APD in EAD initiation, the sarcoplasmic reticulum (SR) was depleted of calcium with caffeine. The first beat post-caffeine was associated with prolonged APD but not an EAD. During {beta}-AR stimulation, increasing ryanodine receptor open probability had no effect on APD but increased APD variability and induced both EADs and delayed afterdepolarisations (DADs). Targeting RyR open probability with K201 reversibly abolished afterdepolarisations. APD variability was a better predictor of EADs than APD alone. During an EAD, changes in [Ca2+]i preceded those of membrane depolarisation and the changes in [Ca2+]i were in the form of calcium sparks. In silico modelling demonstrated that membrane time constant effects account for the delay between changes in [Ca2+]i and membrane potential. In summary, using a drug-induced model of action potential prolongation with {beta}-AR stimulation, EADs are preceded by increased APD variability and an increase in Ca2+ sparks. Targeting SR function abolishes EADs. These results suggest a key role for SR Ca2+ overload in the formation of EADs and indicate that EADs and DADs share common mechanisms. Key PointsO_LIDrugs that prolong the cardiac action potential and ECG QT interval are a major cause of early afterdepolarisations and dangerous ventricular arrhythmias initiated by early afterdepolarisations. C_LIO_LIProlongation of the action potential is widely assumed to be the primary driver of these events. C_LIO_LIWe show that early afterdepolarisations are instead preceded by increased beat-to-beat variability of action potential duration and that this variability has better sensitivity and specificity for early afterdepolarisations than action potential duration. C_LIO_LISmall, spontaneous calcium release events known as calcium sparks occur before membrane depolarisation driving early afterdepolarisations. C_LIO_LISuppressing calcium release from the sarcoplasmic reticulum abolishes early afterdepolarisations, identifying calcium handling instability as potentially a key mechanism of drug-induced arrhythmia. C_LI

Impaired contractility and reduced myocardial energetic reserve underlie heart failure with reduced ejection fraction. Catecholaminergic inotropes such as dobutamine are used to augment cardiac output. However, dobutamine increases Ca{superscript 2} cycling, raising ATP demand and worsening energetic stress. The myotrope CK-138 increases contractility by directly activating myosin, sparing the added energetic cost of Ca{superscript 2} handling. This study compares CK-138 and dobutamine with respect to the relationship between contractile performance and myocardial energetic state, including high-energy phosphate balance, energetic efficiency, and substrate-specific metabolic fluxes. Isolated rat hearts were perfused with escalating concentrations of CK-138 or dobutamine. Contractility was assessed by measuring left ventricular pressure and rate-pressure product. Myocardial energetics were analyzed using 31P-NMR, and metabolic fluxes by 13C NMR and mass spectrometry. Unlike dobutamine, CK-138 increased LV contractility without increasing heart rate or LV end-diastolic pressure. CK-138 preserved ATP and phosphocreatine levels, maintaining a stable phosphocreatine-to-ATP ratio and free energy of ATP hydrolysis, whereas dobutamine progressively depleted both. At comparable workload, dobutamine exhibited higher glycolytic flux and lactate production, indicating greater reliance on glycolysis relative to mitochondrial oxidative metabolism, whereas CK-138 exhibited a 13% higher rate of ATP synthesis and [~]50% lower anaplerotic flux, consistent with preserved mitochondrial efficiency. In conclusion, CK-138 enhances cardiac contractility while preserving myocardial energetic state and substrate utilization. Unlike dobutamine, which depletes ATP reserves and shifts metabolism toward glycolysis, CK-138 maintains ATP homeostasis and supports oxidative metabolism. These findings support cardiac myosin activators, including CK-138 and omecamtiv mecarbil, as a mechanistically distinct class of energy-efficient inotropes.

IntroductionHypertrophic Cardiomyopathy (HCM) is a disease defined by the development of left ventricle hypertrophy. One of the most commonly mutated genes in HCM is cardiac myosin binding protein C (MYBPC3). MYBPC3 protein localizes to the cardiomyocyte sarcomere, but studies have reported detection of both MYBPC3 RNA and protein in non-cardiomyocyte cell populations. Therefore, it was unclear if MYBPC3 expression in non-cardiomyocyte cell populations altered the development of cardiomyopathy caused by MYBPC3 protein deficiency. MethodsWe utilized genetically modified murine models with germline deletion of Mybpc3 exons 3 to 5 (Mybpc3-/-) or cardiomyocyte specific deletion of Mybpc3 exons 3 to 5 (Mybpc3fl/fl; Myh6-Cre). Gene expression was assessed using quantitative RT-PCR. Whole tissue protein levels were assessed using immunoblots. Immunohistochemistry and proximity ligation assays were performed to evaluate in situ protein expression. Echocardiography was utilized to measure left ventricular structure and function. ResultsMybpc3 mRNA was detected in multiple organs including the heart, lung and blood from both humans and mice. Utilizing transgenic murine models with germline or cardiomyocyte specific deletion of Mybpc3 exons 3-5, we discovered that the Mybpc3 mRNA detected in extracardiac locations originated primarily from cardiomyocytes. Likewise, MYBPC3 protein was identified in myocardial tissue but not in other organs and cardiomyocytes were the only cell population in myocardial tissue that had detectable MYBPC3 protein. Importantly, cardiomyocyte deletion of Mybpc3 caused similar pathological myocardial remodeling and alterations in left ventricular function compared to germline deletion of Mybpc3 in all cell populations. ConclusionsOur results show that cardiomyocytes are the primary cell source of Mybpc3 mRNA detected in extracardiac organs and they are the principal cell type responsible for the cardiomyopathy caused by MYBPC3 protein deficiency. These results suggest that selective targeting of cardiomyocytes should be the most efficient approach to treat cardiomyopathies associated with MYBPC3 deficiency.

Pulmonary arterial hypertension (PAH) is a devastating disease with poor outcome affecting relatively young subjects. The arachidonic acid (AA) metabolite, 15-hydroxyeicosatetraenoic acid (15-HETE), has been implicated in the pathogenesis of hypoxia-induced PAH. We tested the hypothesis that genetic deletion of GPR39, the target receptor for 15-HETE, will attenuate PAH. We subjected wild-type (WT) and GPR39 KO to 4 weeks of hypoxia versus normoxia, after which right ventricular and systemic hemodynamics were measured. Immunohistochemistry of lung was performed for pulmonary arteriolar thickness as well as capillary and pericyte density. Lung tissue was also analyzed for AA and 15-HETE levels as well as signaling events (mRNA and protein levels) downtream of GPR39 activation. Unlike WT mice, GPR39 KO mice did not develop PAH. They also exhibited markedly less pulmonary ateriolar remodeling and greater pulmonary capillary density. mRNA expression of genes in the Gq, Gs and G12/13 pathways were upregulated in the WT mice while GPR39 KO hypoxic showed no change in these genes. WT and not GPR39 KO hypoxic mice exhibited enhanced AKT phosphorylation. Downstream of the phosphatidylinositol 3-kinase-AKT pathway, endothelial nitric oxide synthetase was upregulated in both WT hypoxia and GPR39 KO hypoxia mice, while sonic hedgehog was upregulated only in WT hypoxia mice. We conclude that hypoxia-induced aberrant signaling is markedly attenuated with genetic deletion of GPR39, which is associated with less pulmonary arteriolar remodeling and greater capillary density, thus preventing PAH. These results suggest that pharmacological inhibition of GPR39 may offer a novel treatment for PAH.

Background: Cardiac surgery using cardiopulmonary bypass uses controlled hypoperfusion which leads to relative organ damage. Acute kidney injury is the most frequent and most important organ failure, in particular in patients with chronic kidney disease. To date, there are no approved drug treatments that could effectively prevent acute kidney injury. SP16, an agonist of the low-density lipoprotein receptor-related protein 1, has been shown to exert both reno- and cardioprotective effects in preclinical trials. Early clinical use of SP16 in phase I trials was safe. Administration of SP16 had beneficial trends on inflammatory response and infarct size in patients with ST-segment elevation myocardial infarction. The primary objective of this phase IIa trial is to demonstrate that injection of SP16 is safe and superior to placebo in preventing cardiac surgery-associated acute kidney injury within 7 days after surgery. Methods: This randomised, double-blinded, placebo-controlled, single centre study evaluates the efficacy and safety of SP16 in 120 high-risk chronic kidney disease patients with disease stadium G2-G3b undergoing cardiac surgery who are randomised into one of two treatment groups in a 1:1 ratio: SP16 (12 mg) or placebo. The study medication is administered via two subcutaneous injections, with the first dose given before surgery, followed by an additional dose after 9 h. Primary endpoints are the incidence of acute kidney injury during 7 days post-surgery and the frequency of adverse events within 72 h after index surgery. Important secondary endpoints include the incidence of major adverse kidney events at day 90 and impact on cardiac function. Safety assessments encompass adverse events, vital signs, electrocardiograms and routine safety laboratory tests. Additional evaluations include pharmacokinetics and immunological biomarkers. Discussion: This single-centre phase IIa trial will assess the incidence of cardiac surgery-associated acute kidney injury, describing the renoprotective potential of SP16 and its safety profile in patients undergoing cardiac surgery.

Spinal cord injury (SCI) disrupts supraspinal autonomic pathways that regulate cardiovascular function, producing marked blood pressure instability and contributing to secondary injury in peripheral organs. The kidney is particularly vulnerable to these disturbances because renal blood flow (RBF) depends on tightly regulated interactions between neural, myogenic, and vascular control mechanisms. However, how SCI level and chronicity alter dynamic renal autoregulation remains poorly defined. Here, we investigated the effects of high- and low-thoracic SCI on renal hemodynamic control using in vivo blood pressure and RBF recordings in female mice. Hemodynamics were assessed at baseline and during acute sympathetic stimulation induced by norepinephrine (NE; 10 g/kg, i.v.) at 24 h and 4 wk following spinal cord transection at thoracic level 3 (T3) or thoracic level 10 (T10). Time-domain analyses quantified systolic blood pressure recovery, while frequency-domain analyses were used to resolve myogenic and sympathetic contributions to RBF regulation. High-thoracic SCI caused marked disruption of renal vascular responses to acute hypertension, producing paradoxical increases in RBF during NE-induced pressure elevations and sustained reductions in baseline and evoked RBF activity within frequency ranges associated with myogenic and sympathetic vasomotion. These impairments were most pronounced during the chronic phase of injury, consistent with loss of dynamic autoregulatory control and vascular remodeling. In contrast, low-thoracic SCI preserved baseline renal vasomotor activity and demonstrated recovery of dynamic autoregulatory responses over time. These findings identify SCI level and chronicity as critical determinants of renal microvascular regulation and demonstrate that high-thoracic SCI produces persistent autonomic-vascular uncoupling. This disruption of dynamic renal autoregulation represents a previously underappreciated mechanism of secondary organ vulnerability following neurotrauma.

Background: Non-invasive hemoglobin measurement offers a painless and rapid alternative to conventional blood-based testing. The Vivaray Hb pro is a handheld photoplethysmography-based device designed for point-of-care hemoglobin assessment without blood sampling. We evaluated the clinical performance of the Vivaray Hb pro by comparing device-generated hemoglobin values with those obtained from a calibrated laboratory blood cell counter. Methods: In this cross-sectional, non-randomized clinical performance study, participants aged [&ge;]8 years were prospectively recruited. Hemoglobin was measured non-invasively using the Vivaray Hb pro and compared with venous blood samples analyzed on a calibrated Coulter counter. Agreement between methods was assessed using Bland-Altman analysis, including regression-based evaluation for proportional bias. Mean absolute error (MAE) and proportions of measurements within tolerance limits were also calculated. Complete paired measurements were available for 763 individuals. Results: Bland-Altman analysis demonstrated hemoglobin-dependent bias, with overestimation at lower hemoglobin levels and underestimation at higher levels. Regression-based analysis showed proportional bias ({beta}? = -0.178), indicating decreasing difference with increasing hemoglobin concentration. The MAE was 1.5 g/dL but was lower (1.2) in the clinically predominant ranges of 8.1-13 g/dl. Comment: The results support the use of the Vivaray Hb pro as a noninvasive hemoglobin screening and point-of-care assessment tool, particularly in settings where rapid, painless, and repeatable measurements are desirable.

Background: Exercise-based cardiac rehabilitation (CR) improves peak oxygen uptake ([V]O2peak) in patients with coronary heart disease (CHD); however, whether women and men exhibit similar adaptations across the steps of O2 transport remains unknown. We aimed to compare the ventilatory and circulatory determinants of [V]O2peak changes between women and men with CHD following a structured exercise training program. Methods: A total of 28 women (27%) and 75 men (73%) with CHD, matched for age, body mass index, and [V]O2peak (% predicted), underwent maximal cardiopulmonary exercise testing (CPET) before and after 12 weeks of CR. [V]O2peak and minute ventilation ([V]E) were measured breath by breath. Heart rate and cardiac output ([Q]c)were assessed non-invasively using impedance cardiography. Exercise efficiency ({Delta}[V]O2/{Delta}W), alveolar ventilation ([V]A), ventilatory efficiency (OUES), O2 pulse, arteriovenous oxygen content difference (C(a-[v])O2) and gross muscular efficiency (W) were calculated using standard equations. Mixed model analyses (sex x time) were used to compare training-induced changes between sexes. Results: At baseline, values of [V]O2peak (absolute and normalized by fat free mass), [V]E, [V]A, O2 pulse, C(a-[v])O2, {Delta}[V]O2/{Delta}W, W were significantly lower in women than in men with CHD (group effect, p<0.01). [V]O2peak normalized by fat-free mass improved similarly in both sexes after CR (p<0.0001, no significant sex x time interaction). Pulmonary convection ([V]E, [V]A), ventilatory efficiency (OUES), circulatory convection ([Q]c, cardiac index, O2 pulse), and peripheral gross muscular efficiency (W) all improved similarly after CR in women and men (effect sizeXtime effect, p<0.05, no significant group x time interaction). The prevalence of responder categories did not differ between sexes (p=0.826). Conclusion: Women and men with CHD demonstrated equivalent O2 transport phenotype adaptations after CR, with comparable improvements across the O2 transport chain (pulmonary, circulatory, and peripheral determinants of [V]O2peak).

Background: Ischemic stroke occurring in the setting of atrial fibrillation (AF) or carotid atherosclerosis (CA) may reflect distinct underlying biological processes. We integrated proteomic, transcriptomic, and genetic data from different sources to identify circulating proteins and molecular pathways associated with ischemic stroke in patients with AF versus CA. Methods: We conducted a nested proteomic study within the UK Biobank comparing plasma protein levels among ischemic stroke patients with AF (n=539) and CA (n=127). Linear regression models were used to evaluate 2,923 proteins measured using the Olink Explore platform (false discovery rate [FDR] <0.05). In a separate Yale cohort, we evaluated expression of genes encoding identified proteins in thrombectomy clot single-cell RNA sequencing data from ischemic stroke patients with AF (n=7) or CA (n=7), including cell type-specific expression patterns. We then used summary statistics to perform 2-sample Mendelian randomization analyses using cis-protein quantitative trait loci to evaluate associations between genetically predicted levels of proteins identified in prior analyses and ischemic stroke subtypes. Exploratory pathway enrichment analyses were also performed. Results: Twelve circulating proteins differed significantly between ischemic stroke patients with AF versus CA. AF was associated with higher levels of NTproBNP, NPPB, and ACP5, and lower levels of APCS, ANGPT2, PAMR1, PRCP, PROS1, LARP1, F7, F10, and LEO1 (all FDR<0.05). Clot transcriptomic analyses showed corresponding differential expression of ACP5, PRCP, LARP1, ANGPT2, and LEO1 across AF versus CA patients. Pathway analyses suggested enrichment of coagulation-related pathways among proteins associated with CA and natriuretic peptide signaling pathways among proteins associated with AF. Mendelian randomization analyses demonstrated associations between genetically predicted protein levels and ischemic stroke subtypes (AF or CA), including cardioembolic stroke for NTproBNPand ischemic stroke for ANGPT2, ACP5, APCS, and PAMR1. Conclusion: Complementary proteomic, transcriptomic, and genetic analyses identified differing molecular profiles among ischemic stroke patients with AF versus CA. These findings support established biomarkers, including NTproBNP and coagulation-related proteins, while identifying additional candidate pathways that may contribute to biological differences between these stroke-associated conditions. Further validation in clinically adjudicated and longitudinal cohorts is needed.

This study examined the utility of HRV detrended fluctuation analysis alpha-1 (DFA1) to assess readiness-to-train and exercise durability under varying acute training loads. Nineteen trained cyclists completed two 20-minute time-trials (TT) under rested and fatigued conditions. DFA1 was measured during a standardized warm-up (WU), 20-min TT, and standardized cool-down (CD). Power output (PO) and DFA1 responses were compared across conditions, and associations with performance and fitness (W/kg) were examined. DFA1 values declined with increasing WU and CD exercise intensity (p<0.001) and were significantly attenuated following the 20-min TT (p<0.001). While DFA1 profiles did not differ significantly between rested and fatigued conditions, lower pre-TT DFA1 was associated with reduced TT performance (p=0.022; r=0.55), suggesting relevance to training readiness. Additionally, an 18% decline in DFA1 between 10- and 20-min during the TT (p=0.031), and lower post-TT values at matched intensities were observed (p<0.001), indicating physiological perturbation from the 20-min TT. Fitter participants exhibited lower DFA1 values during the 20-min TT (p<0.001; r=-0.77), suggesting a greater capacity to sustain physiological stress. While DFA1 is responsive to exercise intensity and stress, offering potential to assess training readiness and durability, more robust fatigue protocols are needed to validate DFA1 as training load monitoring tool.

Peripheral physiological processes contribute to emotions; however, the extent of the influence of internal signals on subjective emotional experiences remains a subject of debate. MethodsHere we investigated the bodily sensations induced by pharmacological stimulation with adenosine, a potent vasodilator that does not cross the blood-brain barrier, and how these sensations are translated into emotional experiences in 193 patients (94 males, 99 females; mean age 62.6 {+/-} 9.2 years) undergoing pharmacological cardiac stress testing as a part of their clinical assessment for suspected obstructive coronary artery disease. We characterized the subjective experiences induced by adenosine using topographical bodily maps and Likert-rating scales of 16 somatic sensations and 16 emotions. ResultsAdenosine induced strong and consistent bodily sensations related to dyspnea, chest pain, tachycardia, feelings of warmth, and tension in the body. The induced sensations were topographically distinct, with pain and pressure concentrated in the chest, warmth distributed across the upper body, and weakness localized to the torso. These sensations were accompanied by a significant increase in negative emotions, such as anxiety, fear, restlessness, panic, and a decrease in positive emotions of happiness, joy, and calmness. Peak heart rate response predicted the intensity of most bodily and emotional responses. Patients diagnosed with myocardial ischemia did not show heightened sensitivity to adenosine-induced bodily sensations compared to non-ischemic patients, despite exhibiting a blunted tachycardiac reflex. ConclusionThese findings show that peripheral physiological activation alone is sufficient to drive subjective emotional experiences, providing causal evidence for the embodied nature of emotions.