Physiological reports
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Physiological reports · Jun 2019
Effects of a rehabilitation program on microvascular function of CHD patients assessed by near-infrared spectroscopy.
This study aimed to evaluate whether near-infrared spectroscopy (NIRS)-derived reperfusion slope would detect the effects of a 12-week rehabilitation program on lower limb microvascular responsiveness in patients with coronary heart disease (CHD). Ten CHD patients (7 males and 3 females; 57.3 ± 7.6 years) underwent 12 weeks of drug treatment and high-intensity interval training (HIIT), 2 times per week (40 min/session). Microvascular responsiveness was assessed by using NIRS assessment of muscle oxygen saturation (StO2 ) combined with a vascular occlusion test (VOT) (NIRS-VOT). ⋯ The slope 2 StO2 was significantly steeper after 12 weeks of training (4.8 ± 1.6% sec-1 ) compared to the pretraining (3.1 ± 1.6% sec-1 ) (P < 0.05). The area under the curve for the change in the % StO2 signal during re-oxygenation increased significantly from 3494 ± 2372%∙sec at pretraining to 9006 ± 4311%∙sec at post-training (P < 0.05). NIRS-VOT technique detected the improvements of 12 weeks of rehabilitation program in the lower limb microvascular responsiveness of CHD patients.
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Physiological reports · Sep 2018
A1899, PK-THPP, ML365, and Doxapram inhibit endogenous TASK channels and excite calcium signaling in carotid body type-1 cells.
Sensing of hypoxia and acidosis in arterial chemoreceptors is thought to be mediated through the inhibition of TASK and possibly other (e.g., BKCa ) potassium channels which leads to membrane depolarization, voltage-gated Ca-entry, and neurosecretion. Here, we investigate the effects of pharmacological inhibitors on TASK channel activity and [Ca2+ ]i -signaling in isolated neonatal rat type-1 cells. PK-THPP inhibited TASK channel activity in cell attached patches by up to 90% (at 400 nmol/L). ⋯ Paxilline (300 nM) and iberiotoxin (50 nmol/L) also slightly increased [Ca2+ ]i in the presence of A1899 but not in the presence of PK-THPP. In general [Ca2+ ]i responses to TASK inhibitors, alone or in combination with BKCa inhibitors, were smaller than the [Ca2+ ]i responses evoked by hypoxia. These data confirm that TASK channel inhibition is capable of evoking membrane depolarization and robust voltage-gated Ca2+ -entry but suggest that this, even with concomitant inhibition of BKCa channels, may be insufficient to account fully for the [Ca2+ ]i -response to hypoxia.
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Physiological reports · Sep 2018
The influence of esmolol on right ventricular function in early experimental endotoxic shock.
The mechanism by which heart rate (HR) control with esmolol improves hemodynamics during septic shock remains unclear. Improved right ventricular (RV) function, thereby reducing venous congestion, may play a role. We assessed the effect of HR control with esmolol during sepsis on RV function, macrocirculation, microcirculation, end-organ-perfusion, and ventricular-arterial coupling. ⋯ Esmolol improved VACR by decreasing the RV end-systolic pressure. Stopping esmolol showed the reversibility of these effects on the RV and the macrocirculation. In this animal model of acute severe endotoxic septic shock, early administration of esmolol decreased RV-function resulting in venous congestion and an unimproved poor microcirculation despite improved cardiac mechanical efficiency.
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Physiological reports · Sep 2017
Correlation of end tidal carbon dioxide, amplitude spectrum area, and coronary perfusion pressure in a porcine model of cardiac arrest.
Amplitude Spectrum Area (AMSA) values during ventricular fibrillation (VF) correlate with myocardial energy stores and predict defibrillation success. By contrast, end tidal CO2 (ETCO2) values provide a noninvasive assessment of coronary perfusion pressure and myocardial perfusion during cardiopulmonary resuscitation (CPR). ⋯ ETCO2, AMSA, coronary perfusion pressure, cerebral perfusion pressure were lowest with STD CPR, increased with STD CPR + ITD and highest with ACD CPR + ITD Further analysis demonstrated a positive correlation between AMSA and ETCO2 (r = 0.37, P = 0.025) and between AMSA and key hemodynamic parameters (P < 0.05). This study established a moderate positive correlation between ETCO2 and AMSA These findings provide the physiological basis for developing and testing a novel noninvasive method that utilizes either ETCO2 alone or the combination of ETCO2 and AMSA to predict when defibrillation might be successful.
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Physiological reports · Sep 2017
Daily parathyroid hormone administration enhances bone turnover and preserves bone structure after severe immobilization-induced bone loss.
Immobilization, as a result of motor-complete spinal cord injury (SCI), is associated with severe osteoporosis. Whether parathyroid hormone (PTH) administration would reduce bone loss after SCI remains unclear. Thus, female mice underwent sham or surgery to produce complete spinal cord transection. ⋯ In contrast, SCI-PTH animals showed preserved osteoblast and osteoclast numbers and enhanced bone formation rate. Furthermore, SCI-PTH animals had higher levels of bone formation and resorption markers than either SCI- or sham-vehicle groups. Collectively, these findings suggest that intermittent PTH receptor activation is an effective therapeutic strategy to preserve bone integrity after severe immobilization.