Ocular changes over 60 min in supine and prone postures
Some astronauts are returning from long-duration spaceflight with structural ocular and visual changes. We investigated both the transient and sustained effects of changes in the direction of the gravity vector acting on the eye using changes in body posture. Intraocular pressure (IOP; measured by Perkins tonometer), ocular geometry (axial length, corneal thickness, and aqueous depth-noncontact biometer), and the choroid (volume and subfoveal thickness optical coherence tomography) were measured in 10 subjects (5 males and 5 females). Measures were taken over the course of 60 min and analyzed with repeated-measures analysi...
Source: Journal of Applied Physiology - August 10, 2017 Category: Physiology Authors: Anderson, A. P., Babu, G., Swan, J. G., Phillips, S. D., Knaus, D. A., Toutain-Kidd, C. M., Zegans, M. E., Fellows, A. M., Gui, J., Buckey, J. C. Tags: RESEARCH ARTICLE Source Type: research
Effect of age, diet, and tissue type on PCr response to creatine supplementation
Creatine/phosphorylcreatine (PCr) responses to creatine supplementation may be modulated by age, diet, and tissue, but studies assessing this possibility are lacking. Therefore we aimed to determine whether PCr responses vary as a function of age, diet, and tissue. Fifteen children, 17 omnivorous and 14 vegetarian adults, and 18 elderly individuals ("elderly") participated in this study. Participants were given placebo and subsequently creatine (0.3 g·kg–1·day–1) for 7 days in a single-blind fashion. PCr was measured through phosphorus magnetic resonance spectroscopy (31P-MRS) in muscle and brain....
Source: Journal of Applied Physiology - August 10, 2017 Category: Physiology Authors: Solis, M. Y., Artioli, G. G., Otaduy, M. C. G., Leite, C. d. C., Arruda, W., Veiga, R. R., Gualano, B. Tags: RESEARCH ARTICLE Source Type: research
Comparison of the vasodilatory effects of sodium nitroprusside vs. nitroglycerin
The vasodilatory mechanism of Nntroglycerin (NTG) is similar to sodium nitroprusside (SNP) in regard to action on guanosine 3'5'-monophosphate (cyclic GMP) via nitric oxide. However, it is unknown whether NTG can achieve the same magnitude of vasodilation in the forearm as SNP. Therefore, the purpose of the study was to evaluate the differences in forearm blood flow (FBF) and forearm vascular conductance (FVC) during escalating infusions of NTG vs. SNP at similar concentration doses and rates. We measured FBF using venous occlusion plethysmography (VOP) and Doppler ultrasound in eight young, healthy participants (mean age ...
Source: Journal of Applied Physiology - August 10, 2017 Category: Physiology Authors: Ranadive, S. M., Eugene, A. R., Dillon, G., Nicholson, W. T., Joyner, M. J. Tags: INNOVATIVE METHODOLOGY Source Type: research
Increased left ventricular extracellular volume and enhanced twist function in type 1 diabetic individuals
Individuals with type 1 diabetes (T1D) characteristically have high glycemic levels that over time can result in reactive fibrosis and abnormalities in myocardial function. T1 mapping with magnetic resonance imaging (MRI) can estimate the extent of reactive fibrosis by measurement of the extracellular volume fraction (ECV). The extent of alterations in the ECV and associated changes in left ventricular (LV) function and morphology in individuals with T1D is unknown. Fourteen individuals with long-term T1D and 14 sex-, age-, and body mass index-matched controls without diabetes underwent MRI measurement of myocardial T1 and...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Vasanji, Z., Sigal, R. J., Eves, N. D., Isaac, D. L., Friedrich, M. G., Chow, K., Thompson, R. B. Tags: RESEARCH ARTICLE Source Type: research
Individual hemoglobin mass response to normobaric and hypobaric "live high-train low": A one-year crossover study
The purpose of this research was to compare individual hemoglobin mass (Hbmass) changes following a live high-train low (LHTL) altitude training camp under either normobaric hypoxia (NH) or hypobaric hypoxia (HH) conditions in endurance athletes. In a crossover design with a one-year washout, 15 male triathletes randomly performed two 18-day LHTL training camps in either HH or NH. All athletes slept at 2,250 meters and trained at altitudes <1,200 meters. Hbmass was measured in duplicate with the optimized carbon monoxide rebreathing method before (pre) and immediately after (post) each 18-day training camp. Hbmass incre...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Hauser, A., Troesch, S., Saugy, J. J., Schmitt, L., Cejuela-Anta, R., Faiss, R., Steiner, T., Robinson, N., Millet, G. P., Wehrlin, J. P. 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
Physical activity modulates corticospinal excitability of the lower limb in young and old adults
Aging is associated with reduced neuromuscular function, which may be due in part to altered corticospinal excitability. Regular physical activity (PA) may ameliorate these age-related declines, but the influence of PA on corticospinal excitability is unknown. The purpose of this study was to determine the influence of age, sex, and PA on corticospinal excitability by comparing the stimulus-response curves of motor evoked potentials (MEP) in 28 young (22.4 ± 2.2 yr; 14 women and 14 men) and 50 old adults (70.2 ± 6.1 yr; 22 women and 28 men) who varied in activity levels. Transcranial magnetic stimulation was ...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Hassanlouei, H., Sundberg, C. W., Smith, A. E., Kuplic, A., Hunter, S. K. Tags: RESEARCH ARTICLE Source Type: research
The impact of ocular hemodynamics and intracranial pressure on intraocular pressure during acute gravitational changes
Exposure to microgravity causes a bulk fluid shift toward the head, with concomitant changes in blood volume/pressure, and intraocular pressure (IOP). These and other factors, such as intracranial pressure (ICP) changes, are suspected to be involved in the degradation of visual function and ocular anatomical changes exhibited by some astronauts. This is a significant health concern. Here, we describe a lumped-parameter numerical model to simulate volume/pressure alterations in the eye during gravitational changes. The model includes the effects of blood and aqueous humor dynamics, ICP, and IOP-dependent ocular compliance. ...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Nelson, E. S., Mulugeta, L., Feola, A., Raykin, J., Myers, J. G., Samuels, B. C., Ethier, C. R. Tags: RESEARCH ARTICLE Source Type: research
Nonlinearities of heart rate variability in animal models of impaired cardiac control: contribution of different time scales
In this study, the presence of nonlinear dynamics was checked as a function of time scales in three experimental models of rats with different impairment of the cardiac control: namely, rats with heart failure (HF), spontaneously hypertensive rats (SHRs), and sinoaortic denervated (SAD) rats. Multiscale entropy (MSE) and refined MSE (RMSE) were chosen as the discriminating statistic for the surrogate test utilized to detect nonlinearity. Nonlinear dynamics is less present in HF animals at both short and long time scales compared with controls. A similar finding was found in SHR only at short time scales. SAD increased the ...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Silva, L. E. V., Lataro, R. M., Castania, J. A., Silva, C. A. A., Salgado, H. C., Fazan, R., Porta, A. Tags: RESEARCH ARTICLE Source Type: research
Beta-1 vs. beta-2 adrenergic control of coronary blood flow during isometric handgrip exercise in humans
In this study, we simultaneously measured noninvasive indexes of myocardial oxygen supply (i.e., blood velocity in the left anterior descending coronary artery; Doppler echocardiography) and demand [i.e., rate pressure product (RPP) = heart rate x systolic blood pressure) and tested the hypothesis that β1 blockade with esmolol improves coronary exercise hyperemia compared with nonselective β-blockade with propranolol. Eight healthy young men received intravenous infusions of esmolol, propranolol, and saline on three separate days in a single-blind, randomized, crossover design. During each infusion, subjects perf...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Maman, S. R., Vargas, A. F., Ahmad, T. A., Miller, A. J., Gao, Z., Leuenberger, U. A., Proctor, D. N., Muller, M. D. Tags: RESEARCH ARTICLE Source Type: research
Exercise training in Tg{alpha}q*44 mice during the progression of chronic heart failure: cardiac vs. peripheral (soleus muscle) impairments to oxidative metabolism
Cardiac function, skeletal (soleus) muscle oxidative metabolism, and the effects of exercise training were evaluated in a transgenic murine model (Tgαq*44) of chronic heart failure during the critical period between the occurrence of an impairment of cardiac function and the stage at which overt cardiac failure ensues (i.e., from 10 to 12 mo of age). Forty-eight Tgαq*44 mice and 43 wild-type FVB controls were randomly assigned to control groups and to groups undergoing 2 mo of intense exercise training (spontaneous running on an instrumented wheel). In mice evaluated at the beginning and at the end of training ...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Grassi, B., Majerczak, J., Bardi, E., Buso, A., Comelli, M., Chlopicki, S., Guzik, M., Mavelli, I., Nieckarz, Z., Salvadego, D., Tyrankiewicz, U., Skorka, T., Bottinelli, R., Zoladz, J. A., Pellegrino, M. A. Tags: RESEARCH ARTICLE Source Type: research
A model for in vivo analysis of sudomotor sympathetic C-fiber activation and human sweat gland output
Quantitative assessment of small-fiber peripheral neuropathy often involves an evaluation of the interaction between the C-fiber sudomotor nerve and local sweat rate (SR). Typically, some sort of quantitative sudomotor axon reflex test (QSART) is performed to aid in diagnosing small-fiber dysfunction. The currently used QSART demonstrates only moderate test-retest reliability and therefore limits its usefulness in tracking small-fiber dysfunction. A new experimental model to examine small C-fiber function in the skin using intradermal electrical stimulation and simultaneous monitoring of SR is proposed. Using intradermal e...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Mack, G. W. Tags: INNOVATIVE METHODOLOGY Source Type: research
Ten days of repeated local forearm heating does not affect cutaneous vascular function
The aim of the present study was to determine whether 10 days of repeated local heating could induce peripheral adaptations in the cutaneous vasculature and to investigate potential mechanisms of adaptation. We also assessed maximal forearm blood flow to determine whether repeated local heating affects maximal dilator capacity. Before and after 10 days of heat training consisting of 1-h exposures of the forearm to 42°C water or 32°C water (control) in the contralateral arm (randomized and counterbalanced), we assessed hyperemia to rapid local heating of the skin (n = 14 recreationally active young subjects). In add...
Source: Journal of Applied Physiology - August 3, 2017 Category: Physiology Authors: Francisco, M. A., Brunt, V. E., Jensen, K. N., Lorenzo, S., Minson, C. T. Tags: RESEARCH ARTICLE Source Type: research
Aortic arch compliance and idiopathic unilateral vocal fold paralysis
Unilateral vocal fold paralysis (UVP) occurs related to recurrent laryngeal nerve (RLN) impairment associated with impaired swallowing, voice production, and breathing functions. The majority of UVP cases occur subsequent to surgical intervention with approximately 12–42% having no known cause for the disease (i.e., idiopathic). Approximately two-thirds of those with UVP exhibit left-sided injury with the average onset at ≥50 yr of age in those diagnosed as idiopathic. Given the association between the RLN and the subclavian and aortic arch vessels, we hypothesized that changes in vascular tissues would result in ...
Source: Journal of Applied Physiology - August 1, 2017 Category: Physiology Authors: Behkam, R., Roberts, K. E., Bierhals, A. J., Jacobs, M. E., Edgar, J. D., Paniello, R. C., Woodson, G., Vande Geest, J. P., Barkmeier-Kraemer, J. M. Tags: RESEARCH ARTICLE Source Type: research
Inflammatory responses to acute elevations of carbon dioxide in mice
Health risks are described from elevated indoor air carbon dioxide (CO2), which often ranges from 1,000 to 4,000 ppm, but the mechanisms are unknown. Here, we demonstrate that mice exposed for 2 h to 2,000 or 4,000 ppm CO2 exhibit, respectively, 3.4 ± 0.9-fold (SE, n = 6) and 4.1 ± 0.7-fold (n = 10) elevations in circulating microparticles (MPs); neutrophil and platelet activation, and vascular leak in brain, muscle, and distal colon. Interleukin (IL)-1β content of MPs also increases after 2,000 ppm by 3.8 ± 0.6-fold (n = 6) and after 4,000 ppm CO2 by 9.3 ± 1.1-fold (n = 10) greater than co...
Source: Journal of Applied Physiology - August 1, 2017 Category: Physiology Authors: Thom, S. R., Bhopale, V. M., Hu, J., Yang, M. Tags: RESEARCH ARTICLE Source Type: research
