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.

Endurance training attenuates the increase in peripheral chemoreflex sensitivity with intermittent hypoxia
Patients with heart failure and sleep apnea have greater chemoreflex sensitivity, presumably due to intermittent hypoxia (IH), and this is predictive of mortality. We hypothesized that endurance training would attenuate the effect of IH on peripheral chemoreflex sensitivity in healthy humans. Fifteen young healthy subjects (9 female, 26 ± 1 yr) participated. Between visits, 11 subjects underwent 8 wk of endurance training that included running four times/wk at 80% predicted maximum heart rate and interval training, and four control subjects did not change activity. Chemoreflex sensitivity (the slope of ventilation r...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 31, 2017 Category: Physiology Authors: Miller, A. J., Sauder, C. L., Cauffman, A. E., Blaha, C. A., Leuenberger, U. A. Tags: Research Article Source Type: research

Metabolic and functional characterization of effects of developmental temperature in Drosophila melanogaster
The ability of ectotherms to respond to changes in their thermal environment through plastic mechanisms is central to their adaptive capability. However, we still lack knowledge on the physiological and functional responses by which ectotherms acclimate to temperatures during development, and in particular, how physiological stress at extreme temperatures may counteract beneficial acclimation responses at benign temperatures. We exposed Drosophila melanogaster to 10 developmental temperatures covering their entire permissible temperature range. We obtained metabolic profiles and reaction norms for several functional traits...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 31, 2017 Category: Physiology Authors: Schou, M. F., Kristensen, T. N., Pedersen, A., Karlsson, B. G., Loeschcke, V., Malmendal, A. Tags: Research Article Source Type: research

High-intensity interval training, but not continuous training, reverses right ventricular hypertrophy and dysfunction in a rat model of pulmonary hypertension
Exercise is beneficial in pulmonary arterial hypertension (PAH), although studies to date indicate little effect on the elevated pulmonary pressures or maladaptive right ventricle (RV) hypertrophy associated with the disease. For chronic left ventricle failure, high-intensity interval training (HIIT) promotes greater endothelial stimulation and superior benefit than customary continuous exercise training (CExT); however, HIIT has not been tested for PAH. Therefore, here we investigated acute and chronic responses to HIIT vs. CExT in a rat model of monocrotaline (MCT)-induced mild PAH. Six weeks of treadmill training (5 tim...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 31, 2017 Category: Physiology Authors: Brown, M. B., Neves, E., Long, G., Graber, J., Gladish, B., Wiseman, A., Owens, M., Fisher, A. J., Presson, R. G., Petrache, I., Kline, J., Lahm, T. Tags: Research Article Source Type: research

Thyroid hormone-stimulated increases in PGC-1{alpha} and UCP2 promote life history-specific endocrine changes and maintain a lipid-based metabolism
Thyroid hormones (THs) regulate metabolism, but are typically suppressed during times of stressful physiological conditions, including fasting. Interestingly, prolonged fasting in northern elephant seal pups is associated with reliance on a lipid-based metabolism and increased levels of circulating THs that are partially attributed to active secretion as opposed to reduced clearance. This apparent paradox is coupled with complementary increases in cellular TH-mediated activity, suggesting that in mammals naturally adapted to prolonged fasting, THs are necessary to support metabolism. However, the functional relevance of th...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 31, 2017 Category: Physiology Authors: Martinez, B., Sonanez-Organis, J. G., Godoy-Lugo, J. A., Horin, L. J., Crocker, D. E., Ortiz, R. M. Tags: Research Article Source Type: research

Kölliker-Fuse nuclei regulate respiratory rhythm variability via a gain-control mechanism
Respiration varies from breath to breath. On the millisecond timescale of spiking, neuronal circuits exhibit variability due to the stochastic properties of ion channels and synapses. Does this fast, microscopic source of variability contribute to the slower, macroscopic variability of the respiratory period? To address this question, we modeled a stochastic oscillator with forcing; then, we tested its predictions experimentally for the respiratory rhythm generated by the in situ perfused preparation during vagal nerve stimulation (VNS). Our simulations identified a relationship among the gain of the input, entrainment str...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 31, 2017 Category: Physiology Authors: Dhingra, R. R., Dutschmann, M., Galan, R. F., Dick, T. E. Tags: Research Article Source Type: research

Maximum heart rate in brown trout (Salmo trutta fario) is not limited by firing rate of pacemaker cells
This study tests the hypothesis that firing rate of sinoatrial pacemaker cells sets the upper thermal limit of fH in vivo. To this end, temperature dependence of action potential (AP) frequency of enzymatically isolated pacemaker cells (pacemaker rate, fPM), spontaneous beating rate of isolated sinoatrial preparations (fSA), and in vivo fH of the cold-acclimated (4°C) brown trout (Salmo trutta fario) were compared under acute thermal challenges. With rising temperature, fPM steadily increased because of the acceleration of diastolic depolarization and shortening of AP duration up to the break point temperature (TBP) of...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 31, 2017 Category: Physiology Authors: Haverinen, J., Abramochkin, D. V., Kamkin, A., Vornanen, M. Tags: Research Article Source Type: research

Impact of TGF-{beta} inhibition during acute exercise on Achilles tendon extracellular matrix
The purpose of this study was to evaluate the role of TGF-β1 in regulating tendon extracellular matrix after acute exercise. Wistar rats exercised (n = 15) on a treadmill for four consecutive days (60 min/day) or maintained normal cage activity. After each exercise bout, the peritendinous space of each Achilles tendon was injected with a TGF-β1 receptor inhibitor or sham. Independent of group, tendons injected with inhibitor exhibited ~50% lower Smad 3 (Ser423/425) (P < 0.05) and 2.5-fold greater ERK1/2 phosphorylation (P < 0.05) when compared with sham (P < 0.05). Injection of the inhibitor did not alte...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 11, 2017 Category: Physiology Authors: Potter, R. M., Huynh, R. T., Volper, B. D., Arthur, K. A., DLugos, A. C., Sorensen, M. A., Magnusson, S. P., Dickinson, J. M., Hale, T. M., Carroll, C. C. Tags: Research Article Source Type: research

Mesenteric vascular dysregulation and intestinal inflammation accompanies experimental spinal cord injury
Cervical and high thoracic spinal cord injury (SCI) drastically impairs autonomic nervous system function. Individuals with SCI at thoracic spinal level 5 (T5) or higher often present cardiovascular disorders that include resting systemic arterial hypotension. Gastrointestinal (GI) tissues are critically dependent upon adequate blood flow and even brief periods of visceral hypoxia triggers GI dysmotility. The aim of this study was to test the hypothesis that T3-SCI induces visceral hypoperfusion, diminished postprandial vascular reflexes, and concomitant visceral inflammation. We measured in vivo systemic arterial blood pr...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 11, 2017 Category: Physiology Authors: Besecker, E. M., Deiter, G. M., Pironi, N., Cooper, T. K., Holmes, G. M. Tags: Research Article Source Type: research

Separate and shared sympathetic outflow to white and brown fat coordinately regulates thermoregulation and beige adipocyte recruitment
White adipose tissue (WAT) and brown adipose tissue (BAT) are innervated and regulated by the sympathetic nervous system (SNS). It is not clear, however, whether there are shared or separate central SNS outflows to WAT and BAT that regulate their function. We injected two isogenic strains of pseudorabies virus, a retrograde transneuronal viral tract tracer, with unique fluorescent reporters into interscapular BAT (IBAT) and inguinal WAT (IWAT) of the same Siberian hamsters to define SNS pathways to both. To test the functional importance of SNS coordinated control of BAT and WAT, we exposed hamsters with denervated SNS ner...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 11, 2017 Category: Physiology Authors: Nguyen, N. L. T., Barr, C. L., Ryu, V., Cao, Q., Xue, B., Bartness, T. J. Tags: Research Article Source Type: research

Vitamin D supplementation reduces some AT1-AA-induced downstream targets implicated in preeclampsia including hypertension
In this study, we demonstrate that vitamin D improved many factors associated with PE and reduced blood pressure in a hypertensive model without PE features, indicating that vitamin D could be beneficial for various hypertensive disorders of pregnancy. (Source: AJP: Regulatory, Integrative and Comparative Physiology)
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 11, 2017 Category: Physiology Authors: Faulkner, J. L., Amaral, L. M., Cornelius, D. C., Cunningham, M. W., Ibrahim, T., Heep, A., Campbell, N., Usry, N., Wallace, K., Herse, F., Dechend, R., LaMarca, B. Tags: Research Article Source Type: research

Relationship between oxidative stress and brain swelling in goldfish (Carassius auratus) exposed to high environmental ammonia
Buildups of ammonia can cause potentially fatal brain swelling in mammals, but such swelling is reversible in the anoxia- and ammonia-tolerant goldfish (Carassius auratus). We investigated brain swelling and its possible relationship to oxidative stress in the brain and liver of goldfish acutely exposed to high external ammonia (HEA; 5 mmol/l NH4Cl) at two different acclimation temperatures (14°C, 4°C). Exposure to HEA at 14°C for 72h resulted in increased internal ammonia and glutamine concentrations in the brain, and it caused cellular oxidative damage in the brain and liver. However, oxidative damage was mos...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 11, 2017 Category: Physiology Authors: Lisser, D. F. J., Lister, Z. M., Pham-Ho, P. Q. H., Scott, G. R., Wilkie, M. P. Tags: Research Article Source Type: research

Passive heat acclimation improves skeletal muscle contractility in humans
The aim of this study was to investigate the effect of repeated passive heat exposure (i.e., acclimation) on muscle contractility in humans. Fourteen nonheat-acclimated males completed two trials including electrically evoked twitches and voluntary contractions in thermoneutral conditions [Cool: 24°C, 40% relative humidity (RH)] and hot ambient conditions in the hyperthermic state (Hot: 44–50°C, 50% RH) on consecutive days in a counterbalanced order. Rectal temperature was ~36.5°C in Cool and was maintained at ~39°C throughout Hot. Both trials were repeated after 11 days of passive heat acclimation (1...
Source: AJP: Regulatory, Integrative and Comparative Physiology - January 11, 2017 Category: Physiology Authors: Racinais, S., Wilson, M. G., Periard, J. D. Tags: Research Article Source Type: research

Aerobic system analysis based on oxygen uptake and hip acceleration during random over-ground walking activities
In conclusion, PRTS over-ground walking protocol can be used to evaluate the aerobic system dynamics by the simultaneous measurement of Vo2 and hip acceleration. In addition, the aerobic response dynamics from PRBS and PRTS were correlated to maximal Vo2. This study has shown that wearable technologies in combination with assessment of MNG, a novel indicator of system dynamics, open new possibilities to monitor cardiorespiratory health under conditions that better simulate activities of daily living than cardiopulmonary exercise testing performed in a medical environment. (Source: AJP: Regulatory, Integrative and Comparative Physiology)
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 31, 2016 Category: Physiology Authors: Beltrame, T., Hughson, R. L. Tags: Research Article Source Type: research

Altered muscle satellite cell activation following 16 wk of resistance training in young men
We examined the changes in SC content and activation status following a single bout of resistance exercise, before and following a 16-wk progressive resistance training (RT) program in 14 young (25 ± 3 yr) men. Before and after RT, percutaneous biopsies from the vastus lateralis muscle were taken before a single bout of resistance exercise and after 24 and 72 h of postexercise recovery. Muscle fiber size, capillarization, and SC response were determined by immunohistochemistry. Following RT, there was a greater activation of SC after 24 h in response to a single bout of resistance exercise (Pre, 1.4 ± 0.3; 24...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 31, 2016 Category: Physiology Authors: Nederveen, J. P., Snijders, T., Joanisse, S., Wavell, C. G., Mitchell, C. J., Johnston, L. M., Baker, S. K., Phillips, S. M., Parise, G. Tags: Research Article Source Type: research

Loss of UCP1 exacerbates Western diet-induced glycemic dysregulation independent of changes in body weight in female mice
We tested the hypothesis that female mice null for uncoupling protein 1 (UCP1) would have increased susceptibility to Western diet-induced "whitening" of brown adipose tissue (AT) and glucose intolerance. Six-week-old C57BL/6J wild-type (WT) and UCP1 knockout (UCP1–/–) mice, housed at 25°C, were randomized to either a control diet (10% kcal from fat) or Western diet (45% kcal from fat and 1% cholesterol) for 28 wk. Loss of UCP1 had no effect on energy intake, energy expenditure, spontaneous physical activity, weight gain, or visceral white AT mass. Despite similar susceptibility to weight gain compared with...
Source: AJP: Regulatory, Integrative and Comparative Physiology - December 31, 2016 Category: Physiology Authors: Winn, N. C., Vieira-Potter, V. J., Gastecki, M. L., Welly, R. J., Scroggins, R. J., Zidon, T. M., Gaines, T. L., Woodford, M. L., Karasseva, N. G., Kanaley, J. A., Sacks, H. S., Padilla, J. Tags: Research Article Source Type: research