bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Ischaemia‐Reperfusion Injury on Sensory Nerve Control of Vasodilation During a Subsequent Bout of Local Skin Heating in the Forearm
Authors: McGarr Gregory W. , Hodges Gary J. , Cheung Stephen S. 
Published: November 2023

Cutaneous sensory nerves play a vital role in moderating microcirculatory blood flow by releasing vasodilatory neuropeptides in response to various stimuli including local heating. Ischaemia‐reperfusion (I‐R) injury is associated with altered sensory nerve conduction and depletion of sensory neuropeptide stores, which may contribute to an impaired vasodilatory response to local skin heating following the initial ischemic insult. In ten participants we evaluated the contribution of sensory nerves in driving the vasodilatory response to local heating in forearm skin before and after 20 minutes of ischaemia induced by inflating (220 mmHg) a standard blood pressure cuff around the arm. Red blood cell flux, an index of skin blood flow, was examined using laser‐Doppler probes with integrated local heating units. Flux values were then divided by mean arterial pressure and reported as cutaneous vascular conductance (CVC). Local heating was initiated prior to ischaemia and 20 minutes after the release of cuff occlusion at separate skin sites. At each site local temperature was controlled at 33°C and then increased (3°C min−1) to 42°C and held for ~30 min. Following this, local temperature was increased to 44°C for 20 min. Responses were compared between sites with sensory nerves blocked via local anaesthetic (EMLA) cream and untreated (UNTR) sites before and after I‐R. At UNTR sites, I‐R itself had no effect on CVC during the initial vasodilation (5%; P>0.05). However, relative to the UNTR site before I‐R, EMLA reduced CVC during the initial vasodilation by 45% before ischaemia and 20% after I‐R (both P<0.05). Neither I‐R nor EMLA treatment altered CVC during the secondary plateau at 42°C or at maximum heating to 44°C (all P>0.05). I‐R injury caused a significant delay in vasodilatory onset of 36% (P<0.05) at the UNTR site compared to delays of ~76% at EMLA sites before and after I‐R (both P<0.05). The time to initial vasodilatory peak between UNTR sites was unchanged by I‐R (2%; P>0.05). Conversely, it was significantly delayed by 24% (P<0.05) with EMLA application before I‐R, but not after (17%; P>0.05). We conclude that cutaneous sensory nerve impairment caused by 20 minutes of forearm I‐R injury significantly impairs the kinetics of the response to a rapid, non‐painful local heating stimulus, which may be associated with a higher temperature threshold for initiating vasodilation post‐ischaemia. This alteration of sensory nerve function may contribute to persistent tissue hypoxia and impaired thermoregulatory responses to local skin or whole body heating following an initial ischemic insult if temperature is not adequately controlled.Support or Funding InformationNatural Sciences and Engineering Research Council of Canada: Discovery Grant (227912‐12, S.S. Cheung)
Phenotypic and Sex Differences in Microvesicles Released from Cultured Human Brain Microvascular Endothelial Cells in Response to Proinflammatory and Prothrombotic Stimuli
Authors: Hunter Larry W. , Jayachandran Muthuvel , Miller Virginia M. 
Published: November 2023

ObjectiveActivation of brain microvascular endothelium by inflammatory and procoagulant stimuli increases expression of surface cell‐adhesion molecules (CAMs), releases endothelium‐derived microvesicles (MV) into the circulation, and increases permeability of the blood‐brain barrier (BBB). This study evaluated characteristics of MV released from human brain microvascular endothelial cells (HBMEC) following stimulation with proinflammatory or procoagulant stimuli and examined their effect on monolayer permeability.MethodsCultured HBMECs from age‐matched male and female donors were treated for 24 hours with medium supplemented with tumor necrosis factor alpha (TNFα, 20 ng/mL), thrombin (THR, 2 U/mL), or vehicle (control). MVs released into the medium were isolated by differential centrifugation, labeled with annexin V together with antibodies against PECAM‐1, ICAM‐1, E‐selectin, integrin aV, or MCAM, and then analyzed by digital flow cytometry. Permeability (mg/mL FITC‐dextran) of the HBMEC monolayer in response to MV treatment was quantified by fluorescence microplate assay of passage of FITC‐dextran across monolayer cells cultured on microporous supports.ResultsFewer specific antigen‐positive MV were released from unstimulated male compared to female HBMECs. TNFa, but not THR induced early‐stage apoptosis; determined by fluorogenic Caspase‐3 assay in the HBMEC monolayers. TNFa induced release of all MV subtypes from male cells, whereas only integrin aV, ICAM‐1 and E‐selectin positive MVs were released from female cells. THR increased release of PECAM‐1, ICAM‐1, and MCAM positive MVs from male cells, but did not increase release of MV in female cells. After 24 hours exposure to MV (2,500 MV/mL) derived from TNFa‐treated female cells, permeability increased by 17%. Permeabiity was not increased when female cells were exposed to THR‐generated MV.ConclusionsThese results indicate that: 1) inflammatory and procoagulant stimuli release a different array of MV subtypes from male and female HBMECs; 2) specific stimuli‐derived MVs can modify HMBMEC permeability.Support or Funding Information(Supported by NIH P50 AG44170 and the Mayo Clinic Fnd.).
Assessment of Cutaneous Microcirculation Autoregulation with Phase and Linear Based Eulerian Video Magnification
Authors: Golden Michael , Smith Jillian , Oswald Derek , Haselby Cyrus , Murphy Robert , Heinking Kurt P , Henderson Kyle K 
Published: November 2023

IntroductionThe identification of low frequency variations in blood pressure recordings date back to the mid‐1800's. The mechanism for the low frequency oscillation is associated with intrinsic myogenic activity of smooth muscle cells in resistance arteries. Therefore, local metabolic demand modulates blood flow distribution. Non‐invasive assessment of the microcirculation in dermatology, diabetes, skin‐graft, and burn‐injury patients could facilitate assessment of therapeutic interventions. Eulerian Video Magnification (EVM) software was developed by the Massachusetts Institute of Technology (MIT) to magnify subtle changes in motion and color in video recordings. Using this technology, magnification of a video recording may reveal local changes in the cutaneous human microcirculation.HypothesisWe hypothesize that EVM can be used to assess oscillations in cutaneous blood flow velocity.MethodsIRB approval was obtained to acquire physiological data from healthy graduate students (N = 10). Tissue Doppler was used to measure local changes in blood flow velocity on the forehead. Heart rate was assessed with an ECG and subjects breathed in time to a metronome (15 breaths/min) to normalize the effect of ventilation. Videos were processed using MIT's EVM Matlab code to magnify motion (Phase), or color & motion (Linear). All videos were magnified in the frequency range of interest (0.067–1.67 Hz; 4–100 cycles/min) to enhance human physiological frequencies. Gain was set to 50%; and a Gaussian filter was set to level 4. Phase magnification used a pyramid filtering scheme with octaves (1, ½, ¼) to specify the number of times the video is filtered; while linear magnification utilized chrominance attenuation to reduce color changes created by the magnification process. Red, green, and blue color spectrums extracted from magnified videos were analyzed with a Fast Fourier Transform (FFT) to identify magnified frequencies and power.ResultsPhase magnification (motion) and corresponding FFTs suggest strong correlations to heart rate and respiration rate but not tissue Doppler blood flow. On the other hand, linear magnification (color) and accompanying FFTs were strongly correlated to heart rate (r = 0.987; p = 0.001), respiration rate (r = 0.741; p = 0.014), and local tissue Doppler recordings (r = 0.945; p = 0.001).ConclusionThese preliminary data demonstrate that a video recording of a human subject can be magnified with EVM to assess heart rate, respiration rate, and regional blood flow velocity oscillations in the cutaneous microcirculation. EVM may be a useful non‐invasive modality to evaluate changes in microcirculation autoregulation in human subjects.Support or Funding InformationMidwestern University, Chicago College of Osteopathic Medicine, College of Health Sciences
Second Hand Smoke Exposure Increases Susceptibility to Arrhythmogenic Cardiac Alternans
Authors: Wang Zhen , Wang Lianguo , Pinkerton Kent E. , Chen Chao‐Yin , Ripplinger Crystal M. 
Published: November 2023

BackgroundCardiovascular morbidity and mortality are significantly increased by second hand smoke (SHS) exposure in humans. However, the impact of SHS on cardiac electrophysiology, Ca2+ handling, and subsequent arrhythmia risk has not been investigated.MethodsTo investigate the effect of SHS on susceptibility to electrophysiological remodeling and arrhythmias, C57BL/6 male mice were exposed to SHS (3 mg/m3) or filtered air (FA) for 6 hours per day, 5 days per week for 4, 8, or 12 weeks (n = 4–5/group). Following exposure, hearts were excised and Langendorff perfused for optical mapping studies using voltage‐ and Ca2+‐ sensitive dyes (RH237 and Rhod‐2 AM, respectively). Two ventricular pacing protocols were performed: 1) S1–S2 (premature stimulus) to measure action potential duration (APD) and Ca2+ transient restitution across a range of premature stimuli, and 2) continuous pacing at progressively faster frequencies to induce cardiac alternans. For data sets in which SHS and FA groups were compared across a range of pacing frequencies, data were fit with a one phase exponential and the extra sum‐of‐squares (ESS) F test was performed. P<0.05 was considered statistically significant.ResultsSHS exposure did not alter mean APD or AP rise time at any exposure time point. However, the maximal slope of the APD restitution curve was steeper for SHS hearts at longer exposure time points (SHS vs. FA: slope = 0.004 vs. 0.002 normalized APD/ms at 8 weeks, p<0.05 and 0.005 vs. 0.001 normalized APD/ms at 12 weeks, p<0.05), indicating dynamical instability and increased arrhythmia risk following SHS exposure. APD and Ca2+ alternans magnitude progressively increased with increasing pacing frequency in all groups. At 4 and 8 weeks, there were no statistical differences in APD or Ca2+ alternans magnitude between SHS and FA groups. However, following 12 weeks of SHS exposure, both APD and Ca2+ alternans magnitude were significantly increased in the SHS compared to FA group (p<0.05 SHS vs. FA, ESS F test). Alterations in intracellular Ca2+ handling can drive both Ca2+ and APD alternans; therefore, dynamics of Ca2+ release and reuptake were assessed. SHS did not change the time constant of Ca2+ transient decay (tau) at any exposure time point. However, the recovery of Ca2+ transient amplitude with premature stimuli was delayed in SHS compared to FA hearts following 12 weeks of exposure (p<0.05 SHS vs. FA, ESS F test). This result suggests that Ca2+ release via ryanodine receptors may be impaired following SHS exposure.ConclusionSHS exposure increases susceptibility to cardiac alternans, a known precursor to ventricular arrhythmia. Increased alternans magnitude may be due to steepened APD restitution as well as impaired Ca2+‐induced Ca2+ release.Support or Funding InformationNIH R01ES025229 and NIH R01HL111600
N‐Acetylcysteine Influence on Oxidative Stress and Cardiac Remodeling in Rats with Persistent Pressure Overload.
Authors: Reyes David Rafael Abreu , Moreno Camila Rosa , Gomes Mariana Janini , Pagan Luana Urbano , Damatto Ricardo L. , Damatto Felipe C. , Depra Igor Carbalho , Fernandes Ana Angélica Henrique , Okoshi Katashi , Okoshi Marina Politi 
Published: November 2023

The influence of antioxidants on cardiac remodeling during persistent pressure overload is not clear. In this study we evaluated the effects of N‐acetylcysteine administration on cardiac structures and function and oxidative stress in rats with aortic‐stenosis (AS)‐induced heart failure.MethodsEighteen weeks after inducing AS, Wistar rats were assigned into control (Sham, n=16), AS (n=22), and AS treated with N‐acetylcysteine (AS‐NAC, 120 mg/day/kg, n=15) groups. Activity of myocardial antioxidant enzymes was analyzed by spectrophotometry. Statistical analysis was performed by ANOVA and Tukey test.ResultsSerum concentration of malondialdehyde was lower in AS‐NAC than Sham and AS groups [Sham 1.30 (1.18–1.43); AS 1.20 (1.00–1.50); AS‐NAC 0.90 (0.73–1.08) μmol/ml]. Myocardial concentration of hydroperoxide lipid was higher in AS than Sham and AS‐NAC (Sham 199±48.1; AS 301±36.0; AS‐NAC 181±41.3 nmol/g tissue). NAC preserved myocardial total glutathione concentration (Sham 20.8±3.00; AS 12.6±2.92; AS‐NAC 17.6±2.45 nmol/g tissue; p<0.05 AS vs Sham). Activity of catalase, superoxide dismutase, and glutathione peroxidase did not differ between groups. In echocardiographic evaluation, AS and AS‐NAC presented left ventricular concentric hypertrophy with systolic and diastolic dysfunction. NAC did not change ventricular remodeling.ConclusionN‐acetylcysteine administration reduces systemic and myocardial oxidative stress without changing cardiac remodeling in rats with aortic stenosis‐induced heart failure.Support or Funding InformationFAPESP, CNPq, and AUIP/PAEDEx.
Exercise Training Augments Neuronal Nitric Oxide Synthase Dimerization in the Paraventricular Nucleus of Rats with Heart Failure
Authors: Sharma Neeru , Liu Xuefei , Llewellyn Tamra , Patel Kaushik P 
Published: November 2023

Exercise training (ExT) is an established non‐pharmacological therapy that improves the health and quality of life in patients with chronic heart failure (CHF). Exaggerated sympathetic drive characterizes CHF due to an imbalance of the autonomic nervous system, possibly due to reduced neuronal nitric oxide synthase (nNOS) within the paraventricular nucleus (PVN). Previously we have demonstrated that during CHF, the catalytically active dimeric form of nNOS is significantly decreased (~40% decrease in dimer/monomer ratio) with a simultaneous increase in PIN expression (~50%), a protein that uncouples dimeric nNOS to monomers and facilitates its degradation. Dimerization of nNOS also requires tetrahydrobiopterin (BH4) for stability and activity. We have also shown that ExT improves NO‐mediated sympathoinhibition from the PVN. However, the underlying molecular mechanism remains unclear. We hypothesized that ExT restores the sympathetic drive by normalization of the levels and catalytically active form of nNOS by abrogating changes in PIN within the PVN of rats with CHF. CHF was induced in adult male Sprague‐Dawley rats by coronary artery ligation, which reliably mimics CHF in patients with myocardial infarction. After 4‐weeks, Sham and CHF rats were subjected to 3–4 weeks of progressive treadmill exercise. ExT significantly (p < 0.05) restored PIN expression (0.68±0.05 CHF vs 0.40±0.06* ExT‐CHF), and normalized dimer/monomer ratio (0.67±0.04 CHF vs 0.90±0.07* ExT‐CHF), in the PVN of rats with CHF. Moreover, we found decreased GTP cyclohydrolase 1(GCH1) expression: a rate‐limiting enzyme for BH4 biosynthesis in the PVN of CHF rats (0.74±0.03 Sham vs. 0.48±0.02* CHF), suggesting that perhaps reduced BH4 availability may also contribute to decreased nNOS dimer formation. Interestingly, CHF induced reduction in GCH1 expression was improved with ExT (0.48±0.02 CHF vs. 0.70±0.07* ExT‐CHF). Taken together, our findings revealed that ExT‐rectified, decreased PIN and GCH1 expression and improved dimer/monomer ratio of nNOS in the PVN, resulting in increased NO which ameliorates the enhanced sympathetic drive in CHF.Support or Funding InformationSupported by AHA‐14SDG19980007 and NIH HL62222.
The Effects of Quarky Ca2+ Release on Ca2+ Spark in Cardiac Myocytes
Authors: Chen Xudong , Huo Yunlong , Tan Wenchang 
Published: November 2023

Ca2+ sparks and quarks are significant events of Ca2+ releasing from the sarcoplasmic reticulum (SR) in cardiac myocytes, but caused by different releasing mechanisms. The objective of the study is to investigate the effects of Ca2+ quarks on the incidence and properties of Ca2+ sparks theoretically and experimentally. A two‐dimensional (2D) model was developed to simulate Ca2+ sparks and quarks based on the anomalous subdiffusion of Ca2+ in the cytoplasm. The numerical model included some specific features of Ca2+ quarks, such as long duration and small currents. The model was validated against the experimental measurements. It was found that Ca2+ sparks and quarks coexisted at a single release site. Quarky Ca2+ release (QCR) events from rogue ryanodine receptors (RyRs) can activate the clustered RyRs and hence result in Ca2+ sparks with different quantal units. Moreover, the sensitivity analysis showed some variables of rogue RyRs that may exist under pathological conditions significantly affected the incidence of Ca2+ sparks. This study provided some novel insights into the mechanisms of SR Ca2+ releasing events in cardiac myocytes.Support or Funding InformationThis work was supported by the National Natural Science Foundation of China (Grant No. 11272014 and No. 11328201) and the National Key Basic Research Program of China (Grant No. 2013CB531200).
Rewarming Shock Decreases Mitochondrial Respiratory Function in Cardiomyocytes
Authors: Cody Alex , Eshaq Abdulaziz , Schaible Niccole , Han Young Soo , Tveita Torkjel , Sieck Gary 
Published: November 2023

In previous studies, we found that prolonged hypothermia (2 h or greater) followed by rewarming induces cardiac contractile dysfunction (rewarming shock) mimicking the effects of accidental hypothermia followed by rapid rewarming in trauma patients. We found that rewarming shock was also presented in isolated cardiomyocytes in which reduced contractility was attributed to PKA‐mediated TnI phosphorylation and reduced Ca2+ sensitivity. During hypothermia rewarming in cardiomyocytes there is increased production of reactive oxidant species (ROS ‐ superoxide anion), which may trigger the intracellular mechanisms underlying reduced contractility. We hypothesized that in cardiomyocytes, hypothermia/rewarming‐induced ROS production is due to altered mitochondrial respiratory function. To test this hypothesis, isolated cardiomyocytes from 6 rats underwent the following hypothermia/rewarming protocol in which they were electrically stimulated every 2 s: experimental temperature was cooled from 35°C to 15°C during the initial 30 min, then maintained at 15°C for 2 h, followed by rewarming to 35°C in the final 30 min. Time‐matched control cardiomyocytes were also electrically stimulated every 2 s and maintained at 35°C for 3 h. After the 3‐h protocol, cardiomyocytes were placed into separate chambers of an Oroboros Oxygraph (high‐resolution respirometry) to measure O2 consumption rate (OCR) under varying conditions. Initially, basal OCR was measured for 5 min followed by serial exposure to oligomycin (1 μM for 5 min) to block ATP synthase activity, FCCP (0.5 μM repeated 3 times for 5 min each) an H+ ionophore to dissipate mitochondrial membrane potential; and antimycin‐A (0.5 μM for 5 min) to block the electron transport chain. This procedure allowed assessment of the key parameters of mitochondrial respiratory function: basal and maximal respiration (after FCCP exposure), ATP production and proton leak (after oligomycin), and reserve respiratory capacity (calculated after antimycin‐A). We found that compared to control cardiomyocytes, hypothermia/rewarming decreased key parameters of mitochondrial function, which suggests that altered mitochondrial function may have contributed to increased ROS production. In addition, decreased OCR following rewarming may contribute to contractile dysfunction by limiting ATP supply in response to metabolic demand, as well as by contributing to a decline in cell viability (e.g., triggering apoptosis).Support or Funding Information5T32HL105355 (NSS); Norwegian Air Ambulance Foundation (YSH)
Acid Sensing Ion Channel 1 Contributes to Ca2+ Influx in Endothelial Tubes from Small Mesenteric Resistance Arteries
Authors: Garcia Selina M. , Herbert Lindsay M. , Naik Jay S. , Resta Thomas C , Jernigan Nikki L. 
Published: November 2023

Our laboratory has previously shown that acid sensing ion channel 1 (ASIC1) is expressed in pulmonary arterial smooth muscle and contributes to agonist‐induced Ca2+ influx and vasoconstriction secondary to depletion of intracellular Ca2+ stores. In contrast to the vasoconstrictor role of ASIC1 in the pulmonary circulation; in mesenteric arteries, ASIC1 participates in acetylcholine (ACh)‐induced vasodilation. We hypothesized that ACh activates ASIC1‐mediated mesenteric endothelial cell Ca2+ influx through a store‐operated mechanism. To test this hypothesis, we freshly isolated endothelial tubes from small mesenteric resistance arteries (100–200 mm inner diameter). To specifically examine ASIC1‐mediated endothelial cell Ca2+ influx, independent of Ca2+ release from stores, we assessed Mn2+‐quenching of fura‐2 fluorescence in the presence or absence of the specific ASIC1 antagonist, psalmotoxin 1 (PcTX1; 20 nM). Whereas PcTX1 significantly diminished ACh (1 mM)‐induced Ca2+ influx, ASIC1 inhibition was without effect on Ca2+ entry in response to store depletion with cyclopiazonic acid (CPA; 10 μM). We conclude that ASIC1 contributes to ACh‐induced Ca2+ influx in mesenteric endothelial cells; however, this response does not appear to be mediated through a store‐operated mechanism. Future studies will examine the mechanism(s) of receptor‐mediated ASIC1 activation in endothelial cells, as well as potential downstream targets leading to endothelium‐dependent vasodilation.Support or Funding InformationSupported by National Heart, Lung, and Blood Institute Grants R01 HL‐111084 (to N.L. Jernigan), T32 HL007736 (to T.C. Resta), R01 HL132883 (to T.C. Resta), and AHA 16GRNT27700010 (to T.C. Resta).