bsequent reperfusion state.We measured acute vascular responses to heat stress to examine the hypothesis that macrovascular endothelial-dependent dilation is improved in a shear-dependent manner, which is further modified by skin temperature. Twelve healthy males performed whole body heating (+1.3°C esophageal temperature), bilateral forearm heating (∼38°C skin temperature), and a time-matched (∼60 min) control condition on separate days in a counterbalanced order. Bilateral assessments of blood flow and brachial artery flow-mediated dilation (FMD) were performed before and 10 min after each condition with duplex Doppler ultrasound. To isolate the influence of shear stress, a pneumatic cuff was inflated (∼90 mmHg) around the right forearm during each condition to attenuate heat-induced rises in blood flow and shear stress. After forearm heating, FMD increased [cuffed 4.7 (2.9)% to 6.8 (1.5)% and noncuffed 5.1 (2.8)% to 6.4 (2.6)%] in both arms (time P less then 0.01). Whole body heating also increased FMD in the noncuffed arm from 3.hat skin and core temperatures modify the acute vascular responses to passive heating irrespective of the magnitude of increase in shear stress.The study investigated whether high-intensity exercise impairs inspiratory and expiratory muscle perfusion in patients with chronic obstructive pulmonary disease (COPD). We compared respiratory local muscle perfusion between constant-load cycling[sustained at 80% peak work rate (WRpeak)] and voluntary normocapnic hyperpnea reproducing similar work of breathing (WoB) in 18 patients [forced expiratory volume in the first second (FEV1) 58 ± 24% predicted]. Local muscle blood flow index (BFI), using indocyanine green dye, and fractional oxygen saturation (%StiO2) were simultaneously assessed by near-infrared spectroscopy (NIRS) over the intercostal, scalene, rectus abdominis, and vastus lateralis muscles. Cardiac output (impedance cardiography), WoB (esophageal/gastric balloon catheter), and diaphragmatic and extradiaphragmatic respiratory muscle electromyographic activity (EMG) were also assessed throughout cycling and hyperpnea. Minute ventilation, breathing pattern, WoB, and respiratory muscle EMG were comparagh-intensity exercise may partly explain the increased sensations of dyspnea.NEW & NOTEWORTHY We simultaneously assessed the blood flow index (BFI) in three respiratory muscles during hyperpnea and high-intensity constant-load cycling sustained at comparable levels of work of breathing and respiratory neural drive in patients with COPD. We demonstrated that high-intensity exercise impairs respiratory muscle perfusion, as intercostal, scalene, and abdominal BFI increased during hyperpnea but not during cycling. Insufficient adjustment in respiratory muscle perfusion during exercise was associated with greater dyspnea sensations in patients with COPD.Heterogeneous flow-mediated dilation (FMD) and low-flow-mediated constriction (L-FMC) responses have been reported between upper- and lower-limb arteries. Radial artery L-FMC, but not FMD, responses are blunted when endothelial-derived hyperpolarizing factors (EDHFs) or prostaglandin production is inhibited in young adults. However, it is unknown if these mechanisms similarly impact endothelial-dependent responses in the brachial (BA) and popliteal (POP) arteries. We tested whether BA- and POP-L-FMC and FMD would be influenced by independent EDHF and prostaglandin inhibition. Eighteen participants (23 ± 3 yr; 6♀) completed three randomized and double-blinded ultrasound assessments following ingestion of an opaque capsule containing maltodextrin (control), 150 mg of fluconazole (EDHF inhibition), or 500 mg of aspirin (prostaglandin inhibition). POP resting diameter was reduced following fluconazole administration (6.13 ± 0.63 mm vs. 6.19 ± 0.65 mm in control, P = 0.03). Compared with control, fluconazole also d hyperpolarizing factor inhibition conditions. Neither prostaglandins nor endothelial-derived hyperpolarizing factor influenced flow-mediated dilation responses in either the brachial or popliteal artery. In contrast, endothelial-derived hyperpolarizing factor, but not prostaglandins, reduced resting brachial artery blood flow and shear rate and resting popliteal artery diameter, as well as low-flow-mediated constriction responses in both the popliteal and brachial arteries.Mathematical modeling of pressure and flow waveforms in blood vessels using pulse wave propagation (PWP) models has tremendous potential to support clinical decision making. For a personalized model outcome, measurements of all modeled vessel radii and wall thicknesses are required. In clinical practice, however, data sets are often incomplete.  https://www.selleckchem.com/products/guanidine-thiocyanate.html  To overcome this problem, we hypothesized that the adaptive capacity of vessels in response to mechanical load could be utilized to fill in the gaps of incomplete patient-specific data sets. We implemented homeostatic feedback loops in a validated PWP model to allow adaptation of vessel geometry to maintain physiological values of wall stress and wall shear stress. To evaluate our approach, we gathered vascular MRI and ultrasound data sets of wall thicknesses and radii of central and arm arterial segments of 10 healthy subjects. Reference models (i.e., termed RefModel, n = 10) were simulated using complete data, whereas adapted models (AdaptModel, n = 10) used data of h ultrasound and MRI estimates, obtained in humans. Our approach could be used as a tool to facilitate personalized modeling, notably in case of missing data, as routinely found in clinical settings.Rapid-onset vasodilation (ROV) in response to a single muscle contraction is attenuated with aging. Moreover, sex-related differences in muscle blood flow and vasodilation during dynamic exercise have been observed in young and older adults. The purpose of the present study was to explore if sex-related differences in ROV exist in young (n = 36, 25 ± 1 yr) and older (n = 32, 66 ± 1 yr) adults. Subjects performed single forearm contractions at 10%, 20%, and 40% maximal voluntary contraction. Brachial artery blood velocity and diameter were measured with Doppler ultrasound, and forearm vascular conductance (mL·min-1·100 mmHg-1) was calculated from blood flow (mL·min-1) and mean arterial pressure (mmHg) and used as a measure of ROV. Peak ROV was attenuated in women across all relative intensities in the younger and older groups (P less then 0.05). In a subset of subjects with similar absolute workloads (∼5 kg and ∼11 kg), age-related differences in ROV were observed among both women and men (P less then 0.05).