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Source: Journal of Applied Physiology
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Total 52 results found since Jan 2013.
Acute volume loading exacerbates direct ventricular interaction in a model of COPD
Volume loading increases left ventricular (LV) stroke volume (LVSV) through series interaction, but may paradoxically reduce LVSV in the presence of large increases in right ventricular (RV) afterload because of direct ventricular interaction (DVI). RV afterload is often increased in chronic obstructive pulmonary disease (COPD) as a result of pathological changes to respiratory mechanics, namely increased negative intrathoracic pressure (nITP), dynamic lung hyperinflation (DH), and increased pulmonary vascular resistance (PVR). These hallmarks of COPD negatively impact LV hemodynamics in normovolemia. However, it is unknow...
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Cheyne, W. S., Williams, A. M., Harper, M. I., Eves, N. D. Tags: RESEARCH ARTICLE Source Type: research
Cardiac output by pulse contour analysis does not match the increase measured by rebreathing during human spaceflight
This study demonstrated that pulse contour analysis of finger arterial blood pressure to estimate cardiac output failed to track the 46% increase measured by a rebreathing method. These results strongly suggest that alternative methods not dependent on pulse contour analysis are required to track cardiac function in spaceflight.
Source: Journal of Applied Physiology - November 6, 2017 Category: Physiology Authors: Hughson, R. L., Peterson, S. D., Yee, N. J., Greaves, D. K. Tags: RESEARCH ARTICLE Source Type: research
High-altitude champions: birds that live and migrate at altitude
High altitude is physiologically challenging for vertebrate life for many reasons, including hypoxia (low environmental oxygen); yet, many birds thrive at altitude. Compared with mammals, birds have additional enhancements to their oxygen transport cascade, the conceptual series of steps responsible for acquiring oxygen from the environment and transporting it to the mitochondria. These adaptations have allowed them to inhabit a number of high-altitude regions. Waterfowl are a taxon prolific at altitude. This minireview explores the physiological responses of high-altitude waterfowl (geese and ducks), comparing the strateg...
Source: Journal of Applied Physiology - October 26, 2017 Category: Physiology Authors: Laguë, S. L. Tags: REVIEW Source Type: research
Pretreatment with indomethacin results in increased heat stroke severity during recovery in a rodent model of heat stroke
It has been suggested that medications can increase heat stroke (HS) susceptibility/severity. We investigated whether the nonsteroidal anti-inflammatory drug (NSAID) indomethacin (INDO) increases HS severity in a rodent model. Core temperature (Tc) of male, C57BL/6J mice (n = 45) was monitored continuously, and mice were given a dose of INDO [low dose (LO) 1 mg/kg or high dose (HI) 5 mg/kg in flavored treat] or vehicle (flavored treat) before heating. HS animals were heated to 42.4°C and euthanized at three time points for histological, molecular, and metabolic analysis: onset of HS [maximal core temperature (Tc,Max)],...
Source: Journal of Applied Physiology - September 6, 2017 Category: Physiology Authors: Audet, G. N., Dineen, S. M., Stewart, D. A., Plamper, M. L., Pathmasiri, W. W., McRitchie, S. L., Sumner, S. J., Leon, L. R. Tags: RESEARCH ARTICLE Source Type: research
Influence of sex, menstrual cycle, and oral contraceptives on cerebrovascular resistance and cardiorespiratory function during Valsalva or standing
Women experience orthostatic intolerance more than men, and they experience faintness more in the early follicular [i.e., low-hormone (LH)] than luteal [i.e., high-hormone (HH)] phase of the menstrual cycle. Men (n = 13, 25.8 ± 1.8 yr old) and women in the LH (days 2–5; placebo) and HH (days 18–24; high dose) phases of the menstrual cycle with (OC; n = 14, 22.0 ± 0.8 yr old) or without (NOC; n = 12, 21.8 ± 0.5 yr old) oral contraceptive (OC) use underwent the Valsalva maneuver and a supine-sit-stand protocol. Blood pressure, normalized stroke volume [stroke volume index (SVi)], cardiac outp...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Abidi, S., Nili, M., Serna, S., Kim, S., Hazlett, C., Edgell, H. Tags: RESEARCH ARTICLE Source Type: research
Oral N-acetylcysteine and exercise tolerance in mild chronic obstructive pulmonary disease
In conclusion, modulation of plasma redox status with oral NAC treatment was not translated into beneficial effects on central or peripheral components of the oxygen transport pathway, thereby failing to improve exercise tolerance in nonhypoxemic patients with mild COPD.
NEW & NOTEWORTHY Acute antioxidant treatment with N-acetylcysteine (NAC) elevated plasma glutathione but did not modulate central or peripheral components of the O2 transport pathway, thereby failing to improve exercise tolerance in patients with mild chronic obstructive pulmonary disease (COPD).
Source: Journal of Applied Physiology - May 18, 2017 Category: Physiology Authors: Hirai, D. M., Jones, J. H., Zelt, J. T., da Silva, M. L., Bentley, R. F., Edgett, B. A., Gurd, B. J., Tschakovsky, M. E., ODonnell, D. E., Neder, J. A. Tags: RESEARCH ARTICLE Source Type: research
Dynamics of middle cerebral artery blood flow velocity during moderate-intensity exercise
We report a novel method of measuring cerebrovascular blood velocity (MCAv) kinetics under ecologically valid conditions from rest to moderate-intensity exercise. This technique reveals that brain blood flow increases exponentially following the onset of exercise with 1) a strong bilateral coherence in young healthy individuals, and 2) a potential for unique age- and disease-specific profiles.
Source: Journal of Applied Physiology - May 9, 2017 Category: Physiology Authors: Billinger, S. A., Craig, J. C., Kwapiszeski, S. J., Sisante, J.-F. V., Vidoni, E. D., Maletsky, R., Poole, D. C. Tags: INNOVATIVE METHODOLOGY 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 - 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
{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
The protective role of sex hormones in females and exercise prehabilitation in males on sternotomy-induced cranial hypoperfusion in aortic banded mini-swine
During cardiac surgery, specifically sternotomy, cranial hypoperfusion is linked to cerebral ischemia, increased risk of perioperative watershed stroke, and other neurocognitive complications. The purpose of this study was to retrospectively examine the effect of sex hormones in females and exercise prehabilitation in males on median sternotomy-induced changes in cranial perfusion in a large animal model of heart failure. Cranial blood flow (CBF) before and 10 and 60 min poststernotomy was analyzed in eight groups of Yucatan mini-swine: female control, aortic banded, ovariectomized, and ovariectomized + aortic banded; male...
Source: Journal of Applied Physiology - February 28, 2017 Category: Physiology Authors: Olver, T. D., Hiemstra, J. A., Edwards, J. C., Ferguson, B. S., Laughlin, M. H., Emter, C. A. Tags: RESEARCH ARTICLE Source Type: research
Effects of different stresses on cardiac autonomic control and cardiovascular coupling
The objective of this study was to investigate the impacts of different stresses on time-varying autonomic reactivity and cardiovascular coupling. In total, 25 male subjects were recruited. RR intervals (RRI), systolic and diastolic blood pressure (SBP, DBP), stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR) values were collected during rest, mental arithmetic task (MAT), and cold pressor test (CPT). Baroreflex sensitivity (BRS) was derived using the transfer function method. Continuous wavelet transformation of RRI was used to describe the time-variant patterns of autonomic neural activities....
Source: Journal of Applied Physiology - February 28, 2017 Category: Physiology Authors: Xie, L., Liu, B., Wang, X., Mei, M., Li, M., Yu, X., Zhang, J. Tags: RESEARCH ARTICLE Source Type: research
Hemodynamic response to muscle reflex is abnormal in patients with heart failure with preserved ejection fraction
This study demonstrates that diastolic function is important for normal hemodynamic adjustment to the metaboreflex. Moreover, it provides evidence that HFpEF causes hemodynamic impairment similar to that observed in systolic heart failure.
NEW & NOTEWORTHY This study provides evidence that diastolic function is important for normal hemodynamic responses during the activation of the muscle metaboreflex in humans. Moreover, it demonstrates that diastolic impairment leads to hemodynamic consequences similar to those provoked by systolic heart failure. In both cases the target blood pressure is obtained mainly by means of ...
Source: Journal of Applied Physiology - February 13, 2017 Category: Physiology Authors: Roberto, S., Mulliri, G., Milia, R., Solinas, R., Pinna, V., Sainas, G., Piepoli, M. F., Crisafulli, A. Tags: RESEARCH ARTICLE Source Type: research
Unique cytokine and chemokine responses to exertional heat stroke in mice
In this study we used a recently developed mouse EHS model to measure the responses of circulating cytokines/chemokines and cytokine gene expression in muscle. A very rapid increase in circulating IL-6 was observed at maximum core temperature (Tc,max) that peaked at 0.5 h of recovery and disappeared by 3 h. IL-10 was not elevated at any time. This contrasts with PHS where both IL-6 and IL-10 peak at 3 h of recovery. Keratinocyte chemoattractant (KC), granulocyte-colony-stimulating factor (G-CSF), macrophage inflammatory protein (MIP)-2, MIP-1β, and monocyte chemoattractive factor-1 also demonstrated near peak response...
Source: Journal of Applied Physiology - February 2, 2017 Category: Physiology Authors: King, M. A., Leon, L. R., Morse, D. A., Clanton, T. L. Tags: RESEARCH ARTICLE Source Type: research
Single passive leg movement-induced hyperemia: a simple vascular function assessment without a chronotropic response
Passive leg movement (PLM)-induced hyperemia is a novel approach to assess vascular function, with a potential clinical role. However, in some instances, the varying chronotropic response induced by PLM has been proposed to be a potentially confounding factor. Therefore, we simplified and modified the PLM model to require just a single PLM (sPLM), an approach that may evoke a peripheral hemodynamic response, allowing a vascular function assessment, but at the same time minimizing central responses. To both characterize and assess the utility of sPLM, in 12 healthy subjects, we measured heart rate (HR), stroke volume, cardi...
Source: Journal of Applied Physiology - December 31, 2016 Category: Physiology Authors: Venturelli, M., Layec, G., Trinity, J., Hart, C. R., Broxterman, R. M., Richardson, R. S. Tags: INNOVATIVE METHODOLOGY Source Type: research
Healthy aging does not compromise the augmentation of cardiac function during heat stress
During heat stress, stroke volume is maintained in young adults despite reductions in cardiac filling pressures. This is achieved by a general augmentation of cardiac function, highlighted by a left and upward shift of the Frank-Starling relation. In contrast, healthy aged adults are unable to maintain stroke volume during heat stress. We hypothesized that this would be associated with a lack of shift in the Frank-Starling relation. Frank-Starling relations were examined in 11 aged [69 ± 4 (SD) yr, 4 men/7 women] and 12 young (26 ± 5 yr, 6 men/6 women) adults during normothermic and heat stress (1.5°C inc...
Source: Journal of Applied Physiology - October 2, 2016 Category: Physiology Authors: Gagnon, D., Romero, S. A., Ngo, H., Sarma, S., Cornwell, W. K., Poh, P. Y. S., Stoller, D., Levine, B. D., Crandall, C. G. Tags: ARTICLES Source Type: research
