{beta}1-Blockade increases maximal apnea duration in elite breath-hold divers
We hypothesized that the cardioselective β1-adrenoreceptor antagonist esmolol would improve maximal apnea duration in elite breath-hold divers. In elite national-level divers (n = 9), maximal apneas were performed in a randomized and counterbalanced order while receiving either iv esmolol (150 μg·kg–1·min–1) or volume-matched saline (placebo). During apnea, heart rate (ECG), beat-by-beat blood pressure, stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) were measured (finger photoplethysmography). Myocardial oxygen consumption (MVo2) was estimated from rate pres...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Hoiland, R. L., Ainslie, P. N., Bain, A. R., MacLeod, D. B., Stembridge, M., Drvis, I., Madden, D., Barak, O., MacLeod, D. M., Dujic, Z. Tags: RESEARCH ARTICLE Source Type: research
Heart rate kinetics during exercise in patients with subclinical hypothyroidism
Studies suggest that patients with subclinical hypothyroidism (SH) have sympathovagal imbalance, which could lead to a slower heart rate (HR) response in the transition from rest to exercise. Thus the objective of this study was to investigate the behavior of the HR kinetics in patients with SH during the transition from rest to exercise. The study included 18 SH women [thyroid stimulating hormone (TSH) = 6.95 ± 2.94 μIU/ml and free thyroxine (FT4) = 0.96 ± 0.15 ng/dl] and 17 euthyroid women (TSH = 2.28 ± 0.84 μIU/ml and FT4 = 0.98 ± 0.07 ng/dl). Both groups were matched for physical activ...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Almas, S. P., Werneck, F. Z., Coelho, E. F., Teixeira, P. d. F. d. S., Vaisman, M. Tags: RESEARCH ARTICLE Source Type: research
Losartan reduces the immediate and sustained increases in muscle sympathetic nerve activity after hyperacute intermittent hypoxia
This study demonstrates for the first time in humans that losartan, an angiotensin receptor blocker (ARB), abrogates the acute and immediately persistent increases in muscle sympathetic nerve activity and arterial pressure in response to acute intermittent hypoxia. This investigation, along with others, provides important beginning translational evidence for using ARBs in treatment of the intermittent hypoxia observed in obstructive sleep apnea patients. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Jouett, N. P., Moralez, G., Raven, P. B., Smith, M. L. Tags: RESEARCH ARTICLE Source Type: research
The cerebrovascular response to lower-body negative pressure vs. head-up tilt
This study showed that the pronounced reduction in end-tidal Pco2 together with gravitational effects on the brain circulation lead to a larger decline in cerebral blood flow velocity in response to head-up tilt than during lower-body negative pressure. This should be taken into account when employing lower-body negative pressure as MRI-compatible alternative to orthostatic stress. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Bronzwaer, A.-S. G. T., Verbree, J., Stok, W. J., Daemen, M. J. A. P., van Buchem, M. A., van Osch, M. J. P., van Lieshout, J. J. Tags: RESEARCH ARTICLE Source Type: research
Carotid {beta}-stiffness index is associated with slower processing speed but not working memory or white matter integrity in healthy middle-aged/older adults
This study adds to the field by demonstrating that the age-related increases in carotid artery stiffness, but not aortic stiffness, is independently and selectively associated with slower processing speed but not working memory among middle-aged/older adults with low cardiovascular disease risk factor burden. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: DuBose, L. E., Voss, M. W., Weng, T. B., Kent, J. D., Dubishar, K. M., Lane-Cordova, A., Sigurdsson, G., Schmid, P., Barlow, P. B., Pierce, G. L. Tags: RESEARCH ARTICLE Source Type: research
Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses
Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel "virtual EI...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Roth, C. J., Becher, T., Frerichs, I., Weiler, N., Wall, W. A. Tags: RESEARCH ARTICLE Source Type: research
Exploring new heights with pulmonary functional imaging: insights into high-altitude pulmonary edema
(Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Fain, S. B., Eldridge, M. W. Tags: INVITED EDITORIAL Source Type: research
Susceptibility to high-altitude pulmonary edema is associated with a more uniform distribution of regional specific ventilation
In conclusion, ventilation heterogeneity does not change with short-term hypoxia irrespective of HAPE susceptibility, and lesser rather than greater ventilation heterogeneity is observed in HAPE-susceptible subjects. This suggests that the basis for uneven HPV in HAPE involves vascular phenomena.
NEW & NOTEWORTHY Uneven hypoxic pulmonary vasoconstriction (HPV) is thought to incite high-altitude pulmonary edema (HAPE). We evaluated whether greater heterogeneity of ventilation is also a feature of HAPE-susceptible subjects compared with HAPE-resistant subjects. Contrary to our hypothesis, ventilation heterogeneity was le...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Patz, M. D., Sa, R. C., Darquenne, C., Elliott, A. R., Asadi, A. K., Theilmann, R. J., Dubowitz, D. J., Swenson, E. R., Prisk, G. K., Hopkins, S. R. Tags: RESEARCH ARTICLE Source Type: research
Contractile efficiency of dystrophic mdx mouse muscle: in vivo and ex vivo assessment of adaptation to exercise of functional end points
Progressive weakness is a typical feature of Duchenne muscular dystrophy (DMD) patients and is exacerbated in the benign mdx mouse model by in vivo treadmill exercise. We hypothesized a different threshold for functional adaptation of mdx muscles in response to the duration of the exercise protocol. In vivo weakness was confirmed by grip strength after 4, 8, and 12 wk of exercise in mdx mice. Torque measurements revealed that exercise-related weakness in mdx mice correlated with the duration of the protocol, while wild-type (WT) mice were stronger. Twitch and tetanic forces of isolated diaphragm and extensor digitorum long...
Source: Journal of Applied Physiology - April 5, 2017 Category: Physiology Authors: Capogrosso, R. F., Mantuano, P., Cozzoli, A., Sanarica, F., Massari, A. M., Conte, E., Fonzino, A., Giustino, A., Rolland, J.-F., Quaranta, A., De Bellis, M., Camerino, G. M., Grange, R. W., De Luca, A. Tags: RESEARCH ARTICLE Source Type: research
Exercise training decreases NADPH oxidase activity and restores skeletal muscle mass in heart failure rats
This study demonstrates, for the first time, the contribution of aerobic exercise training (AET) in decreasing muscle NADPH oxidase activity associated with reduced reactive oxygen species production and systemic inflammation, which diminish NF-B overactivation, p38 phosphorylation, and ubiquitin proteasome system hyperactivity. These molecular changes counteract plantaris atrophy in trained myocardial infarction-induced heart failure rats. Our data provide new evidence into how AET may regulate protein degradation and thus prevent skeletal muscle atrophy. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 1, 2017 Category: Physiology Authors: Cunha, T. F., Bechara, L. R. G., Bacurau, A. V. N., Jannig, P. R., Voltarelli, V. A., Dourado, P. M., Vasconcelos, A. R., Scavone, C., Ferreira, J. C. B., Brum, P. C. Tags: RESEARCH ARTICLE Source Type: research
Contribution of rostral fluid shift to intrathoracic airway narrowing in asthma
In asthma, supine posture and sleep increase intrathoracic airway narrowing. When humans are supine, because of gravity fluid moves out of the legs and accumulates in the thorax. We hypothesized that fluid shifting out of the legs into the thorax contributes to the intrathoracic airway narrowing in asthma. Healthy and asthmatic subjects sat for 30 min and then lay supine for 30 min. To simulate overnight fluid shift, supine subjects were randomized to receive increased fluid shift out of the legs with lower body positive pressure (LBPP, 10-30 min) or none (control) and crossed over. With forced oscillation at 5 Hz, respira...
Source: Journal of Applied Physiology - April 1, 2017 Category: Physiology Authors: Bhatawadekar, S. A., Inman, M. D., Fredberg, J. J., Tarlo, S. M., Lyons, O. D., Keller, G., Yadollahi, A. Tags: RESEARCH ARTICLE Source Type: research
Adenosine receptor-dependent signaling is not obligatory for normobaric and hypobaric hypoxia-induced cerebral vasodilation in humans
Hypoxia increases cerebral blood flow (CBF) with the underlying signaling processes potentially including adenosine. A randomized, double-blinded, and placebo-controlled design, was implemented to determine if adenosine receptor antagonism (theophylline, 3.75 mg/Kg) would reduce the CBF response to normobaric and hypobaric hypoxia. In 12 participants the partial pressures of end-tidal oxygen (PETO2) and carbon dioxide (PETCO2), ventilation (pneumotachography), blood pressure (finger photoplethysmography), heart rate (electrocardiogram), CBF (duplex ultrasound), and intracranial blood velocities (transcranial Doppler ultras...
Source: Journal of Applied Physiology - April 1, 2017 Category: Physiology Authors: Hoiland, R. L., Bain, A. R., Tymko, M. M., Rieger, M. G., Howe, C. A., Willie, C. K., Hansen, A. B., Flück, D., Wildfong, K. W., Stembridge, M., Subedi, P., Anholm, J., Ainslie, P. N. Tags: RESEARCH ARTICLE Source Type: research
Sleep during an Antarctic summer expedition: new light on "polar insomnia"
Sleep complaints are consistently cited as the most prominent health and well-being problem in Arctic and Antarctic expeditions, without clear evidence to identify the causal mechanisms. The present investigation aimed at studying sleep and determining circadian regulation and mood during a 4-mo Antarctic summer expedition. All data collection was performed during the continuous illumination of the Antarctic summer. After an habituation night and acclimatization to the environment (3 wk), ambulatory polysomnography (PSG) was performed in 21 healthy male subjects, free of medication. An 18-h profile (saliva sampling every 2...
Source: Journal of Applied Physiology - April 1, 2017 Category: Physiology Authors: Pattyn, N., Mairesse, O., Cortoos, A., Marcoen, N., Neyt, X., Meeusen, R. Tags: RESEARCH ARTICLE Source Type: research
Moderate-intensity resistance exercise alters skeletal muscle molecular and cellular structure and function in inactive older adults with knee osteoarthritis
High-intensity resistance exercise (REX) training increases physical capacity, in part, by improving muscle cell size and function. Moderate-intensity REX, which is more feasible for many older adults with disease and/or disability, also increases physical function, but the mechanisms underlying such improvements are not understood. Therefore, we measured skeletal muscle structure and function from the molecular to the tissue level in response to 14 wk of moderate-intensity REX in physically inactive older adults with knee osteoarthritis (n = 17; 70 ± 1 yr). Although REX training increased quadriceps muscle cross-se...
Source: Journal of Applied Physiology - April 1, 2017 Category: Physiology Authors: Miller, M. S., Callahan, D. M., Tourville, T. W., Slauterbeck, J. R., Kaplan, A., Fiske, B. R., Savage, P. D., Ades, P. A., Beynnon, B. D., Toth, M. J. Tags: RESEARCH ARTICLE Source Type: research
Effect of adrenal medullectomy on metabolic responses to chronic intermittent hypoxia in the frequently sampled intravenous glucose tolerance test
We report that IH did not affect fasting glucose and insulin levels nor insulin sensitivity and insulin secretion during, whereas glucose effectiveness was decreased. Adrenal medullectomy decreased fasting blood glucose and insulin levels in mice exposed to IH but had no effect on glucose metabolism, insulin secretion, and insulin sensitivity. (Source: Journal of Applied Physiology)
Source: Journal of Applied Physiology - April 1, 2017 Category: Physiology Authors: Shin, M.-K., Han, W., Joo, H., Bevans-Fonti, S., Shiota, M., Stefanovski, D., Polotsky, V. Y. Tags: RESEARCH ARTICLE Source Type: research
