AJP: Regulatory, Integrative and Comparative Physiology This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Comparative NMR and NIRS analysis of oxygen-dependent metabolism in exercising finger flexor muscles
Muscle contraction requires the physiology to adapt rapidly to meet the surge in energy demand. To investigate the shift in metabolic control, especially between oxygen and metabolism, researchers often depend on near-infrared spectroscopy (NIRS) to measure noninvasively the tissue O2. Because NIRS detects the overlapping myoglobin (Mb) and hemoglobin (Hb) signals in muscle, interpreting the data as an index of cellular or vascular O2 requires deconvoluting the relative contribution. Currently, many in the NIRS field ascribe the signal to Hb. In contrast, 1H NMR has only detected the Mb signal in contracting muscle, and co...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 5, 2017 Category: Physiology Authors: Bendahan, D., Chatel, B., Jue, T. Tags: Research Article Source Type: research

Fluid replacement modulates oxidative stress- but not nitric oxide-mediated cutaneous vasodilation and sweating during prolonged exercise in the heat
The roles of nitric oxide synthase (NOS), reactive oxygen species (ROS), and angiotensin II type 1 receptor (AT1R) activation in regulating cutaneous vasodilation and sweating during prolonged (≥60 min) exercise are currently unclear. Moreover, it remains to be determined whether fluid replacement (FR) modulates the above thermoeffector responses. To investigate, 11 young men completed 90 min of continuous moderate intensity (46% Vo2peak) cycling performed at a fixed rate of metabolic heat production of 600 W (No FR condition). On a separate day, participants completed a second session of the same protocol while receivi...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 5, 2017 Category: Physiology Authors: McNeely, B. D., Meade, R. D., Fujii, N., Seely, A. J. E., Sigal, R. J., Kenny, G. P. Tags: Research Article Source Type: research

The plateau in the NIRS-derived [HHb] signal near the end of a ramp incremental test does not indicate the upper limit of O2 extraction in the vastus lateralis
This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O2) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O2 extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg, 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O2 extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBFOCC1) ...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 5, 2017 Category: Physiology Authors: Inglis, E. C., Iannetta, D., Murias, J. M. Tags: Research Article Source Type: research

Small functional If current in sinoatrial pacemaker cells of the brown trout (Salmo trutta fario) heart despite strong expression of HCN channel transcripts
We examined the presence and activity of HCN channels in the brown trout (Salmo trutta fario) sinoatrial (SA) pacemaker cells and their putative role in heart rate (fH) regulation. Six HCN transcripts (HCN1, HCN2a, HCN2ba, HCN2bb, HCN3, and HCN4) were expressed in the brown trout heart. The total HCN transcript abundance was 4.0 and 4.9 times higher in SA pacemaker tissue than in atrium and ventricle, respectively. In the SA pacemaker, HCN3 and HCN4 were the main isoforms representing 35.8 ± 2.7 and 25.0 ± 1.5%, respectively, of the total HCN transcripts. Only a small If with a mean current density of –...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 5, 2017 Category: Physiology Authors: Hassinen, M., Haverinen, J., Vornanen, M. Tags: Research Article Source Type: research

A new paradigm of sodium regulation in inflammation and hypertension
Dysregulation of sodium (Na+) balance is a major cause of hypertensive cardiovascular disease. The current dogma is that interstitial Na+ readily equilibrates with plasma and that renal excretion and reabsorption is sufficient to regulate extracellular fluid volume and control blood pressure. These ideas have been recently challenged by the discovery that Na+ accumulates in tissues without commensurate volume retention and activates immune cells, leading to hypertension and autoimmune disease. However, objections have been raised to this new paradigm, with some investigators concerned about where and how salt is stored in ...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 5, 2017 Category: Physiology Authors: Kirabo, A. Tags: Review Source Type: research

Immune regulation of systemic hypertension, pulmonary arterial hypertension, and preeclampsia: shared disease mechanisms and translational opportunities
Systemic hypertension, preeclampsia, and pulmonary arterial hypertension (PAH) are diseases of high blood pressure in the systemic or pulmonary circulation. Beyond the well-defined contribution of more traditional pathophysiological mechanisms, such as changes in the renin–angiotensin–aldosterone system, to the development of these hypertensive disorders, there is substantial clinical evidence supporting an important role for inflammation and immunity in the pathogenesis of each of these three conditions. Over the last decade, work in small animal models, bearing targeted deficiencies in specific cytokines or i...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 5, 2017 Category: Physiology Authors: Jafri, S., Ormiston, M. L. Tags: Review Source Type: research

Variation in Akt protein kinases in human populations
The three Akt kinases are related proteins that are essential for normal growth and metabolic regulation and are implicated as key signaling mediators in many physiological and pathophysiological processes. Each Akt is activated by common biochemical signals that act downstream of growth factor and hormone receptors via phosphatidylinositol-3 kinase, and each controls several downstream pathways. The importance of Akt actions in human physiology is strengthened by the rarity of modifying mutations in their genes and by the devastating impact caused by these mutations on growth and development and in disorders such as cance...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Rotwein, P. Tags: Research Article Source Type: research

White-nose syndrome increases torpid metabolic rate and evaporative water loss in hibernating bats
Fungal diseases of wildlife typically manifest as superficial skin infections but can have devastating consequences for host physiology and survival. White-nose syndrome (WNS) is a fungal skin disease that has killed millions of hibernating bats in North America since 2007. Infection with the fungus Pseudogymnoascus destructans causes bats to rewarm too often during hibernation, but the cause of increased arousal rates remains unknown. On the basis of data from studies of captive and free-living bats, two mechanistic models have been proposed to explain disease processes in WNS. Key predictions of both models are that WNS-...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: McGuire, L. P., Mayberry, H. W., Willis, C. K. R. Tags: Research Article Source Type: research

The in vitro zebrafish heart as a model to investigate the chronotropic effects of vapor anesthetics
In this study, isolated zebrafish hearts were significantly bradycardic during exposure to the vapor anesthetics sevoflurane (SEVO), desflurane (DES), and isoflurane (ISO). Bradycardia induced by DES and ISO continued during pharmacological blockade of the intracardiac portion of the autonomic nervous system, but the chronotropic effect of SEVO was eliminated during blockade. Bradycardia evoked by vagosympathetic nerve stimulation was augmented during DES and ISO exposure; nerve stimulation during SEVO exposure had no effect. Together, these results support the hypothesis that the cardiac chronotropic effect of SEVO occurs...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Stoyek, M. R., Schmidt, M. K., Wilfart, F. M., Croll, R. P., Smith, F. M. Tags: Research Article Source Type: research

Use of radiotelemetry to assess perinatal cardiac function in the ovine fetus and newborn
The late gestation fetal ECG (fECG) has traditionally been difficult to characterize due to the low fECG signal relative to high maternal noise. Although new technologies have improved the feasibility of its acquisition and separation, little is known about its development in late gestation, a period in which the fetal heart undergoes extensive maturational changes. Here, we describe a method for the chronic implantation of radiotelemetry devices into late gestation ovine fetuses to characterize parameters of the fECG following surgery, throughout late gestation, and in the perinatal period. We found no significant changes...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Antolic, A., Wood, C. E., Keller-Wood, M. Tags: Review Source Type: research

Baroreflex and neurovascular responses to skeletal muscle mechanoreflex activation in humans: an exercise in integrative physiology
Cardiovascular adjustments to exercise resulting in increased blood pressure (BP) and heart rate (HR) occur in response to activation of several neural mechanisms: the exercise pressor reflex, central command, and the arterial baroreflex. Neural inputs from these feedback and feedforward mechanisms integrate in the cardiovascular control centers in the brain stem and modulate sympathetic and parasympathetic neural outflow, resulting in the increased BP and HR observed during exercise. Another specific consequence of the central neural integration of these inputs during exercise is increased sympathetic neural outflow direc...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Drew, R. C. Tags: Review Source Type: research

The differential role of reactive oxygen species in early and late stages of cancer
The large doses of vitamins C and E and β-carotene used to reduce reactive oxygen species (ROS) production and oxidative damages in cancerous tissue have produced disappointing and contradictory results. This therapeutic conundrum was attributed to the double-faced role of ROS, notably, their ability to induce either proliferation or apoptosis of cancer cells. However, for a ROS-inhibitory approach to be effective, it must target ROS when they induce proliferation rather than apoptosis. On the basis of recent advances in redox biology, this review underlined a differential regulation of prooxidant and antioxidant syst...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Assi, M. Tags: Review Source Type: research

Optogenetics and pharmacogenetics: principles and applications
Remote and selective spatiotemporal control of the activity of neurons to regulate behavior and physiological functions has been a long-sought goal in system neuroscience. Identification and subsequent bioengineering of light-sensitive ion channels (e.g., channelrhodopsins, halorhodopsin, and archaerhodopsins) from the bacteria have made it possible to use light to artificially modulate neuronal activity, namely optogenetics. Recent advance in genetics has also allowed development of novel pharmacological tools to selectively and remotely control neuronal activity using engineered G protein-coupled receptors, which can be ...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Jiang, J., Cui, H., Rahmouni, K. Tags: Review Source Type: research

Editorial team changes in 2018
(Source: AJP: Regulatory, Integrative and Comparative Physiology)
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 1, 2017 Category: Physiology Authors: Samson, W. K. Tags: Editorial Source Type: research

Obesity modulates diaphragm curvature in subjects with and without COPD
Obesity is a common comorbidity of chronic obstructive pulmonary disease (COPD) and has been associated with worse outcomes. However, it is unknown whether the interaction between obesity and COPD modulates diaphragm shape and consequently its function. The body mass index (BMI) has been used as a correlate of obesity. We tested the hypothesis that the shape of the diaphragm muscle and size of the ring of its insertion in non-COPD and COPD subjects are modulated by BMI. We recruited 48 COPD patients with postbronchiodilator forced expiratory volume in 1 s (FEV1)-to-forced vital capacity (FVC) < 0.7 and 29 age-matched sm...
Source: AJP: Regulatory, Integrative and Comparative Physiology - November 9, 2017 Category: Physiology Authors: Boriek, A. M., Lopez, M. A., Velasco, C., Bakir, A. A., Frolov, A., Wynd, S., Babb, T. G., Hanania, N. A., Hoffman, E. A., Sharafkhaneh, A. Tags: Research Article Source Type: research