Impact of skin temperature and hydration on plasma volume responses during exercise

2014 ◽  
Vol 117 (4) ◽  
pp. 413-420 ◽  
Author(s):  
Robert W. Kenefick ◽  
Kurt J. Sollanek ◽  
Nisha Charkoudian ◽  
Michael N. Sawka
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Steady State ◽  
Skin Temperature ◽  
Plasma Volume ◽  
Acute Exercise ◽  
Cycle Ergometry ◽  
Fluid Loss ◽  
Plasma Loss ◽  
Potential Interactions

Heat stress and hydration may both alter plasma volume (PV) responses during acute exercise; potential interactions have not been fully studied. The purpose of this study was to determine the effect of graded elevations in skin temperature (Tsk) on PV changes during steady-state exercise under conditions of euhydration (EU) and hypohydration (HYPO, −4% of body mass). Thirty-two men (22 ± 4 yr) were divided into four cohorts ( n = 8 each) and completed EU and HYPO trials in one environment [ambient temperature (Ta) 10, 20, 30, and 40°C]. Thirty minutes of cycle ergometry (50% V̇o2peak) was performed. Core (Tre) and mean skin (Tsk) temperatures were measured; changes in PV, total circulating protein (TCP), and mean arterial pressure (MAP) were calculated; and skin blood flow (SkBF) was estimated. Hypohydration decreased ( P < 0.05) PV by 200 ml (−5.7%) but did not alter TCP. Plasma loss was not different between EU and HYPO during exercise at any Ta. Plasma losses were greater ( P < 0.05) with elevated Ta with an average −130, −174, −294, and −445 ml losses during the 10, 20, 30, and 40°C trials, respectively. Significant ( P < 0.05) correlations ( r = 0.50 to 0.84) were found between ΔTCP and ΔPV during exercise when Tsk was cool/warm (<33°C; Ta 10, 20, and 30°C), but not at 40°C (high Tsk). We conclude that 1) graded skin warming proportionally accentuated plasma loss; 2) plasma loss was associated with plasma protein efflux at lower Tsk and SkBF; 3) at high Tsk, additional plasma loss likely results from increased net filtration at the capillaries; and 4) HYPO did not alter vascular fluid loss during exercise in any environment.

Active cutaneous vasodilation in resting humans during mild heat stress

2005 ◽  
Vol 98 (3) ◽  
pp. 829-837 ◽  
Author(s):  
Yoshi-Ichiro Kamijo ◽  
Kichang Lee ◽  
Gary W. Mack
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Temperature ◽  
Skin Blood Flow ◽  
Sweat Rate ◽  
Mean Skin Temperature ◽  
Local Skin ◽  
Mild Heat ◽  
Normal Core ◽  
Local Sweat Rate

The role of skin temperature in reflex control of the active cutaneous vasodilator system was examined in six subjects during mild graded heat stress imposed by perfusing water at 34, 36, 38, and 40°C through a tube-lined garment. Skin sympathetic nerve activity (SSNA) was recorded from the peroneal nerve with microneurography. While monitoring esophageal, mean skin, and local skin temperatures, we recorded skin blood flow at bretylium-treated and untreated skin sites by using laser-Doppler velocimetry and local sweat rate by using capacitance hygrometry on the dorsal foot. Cutaneous vascular conductance (CVC) was calculated by dividing skin blood flow by mean arterial pressure. Mild heat stress increased mean skin temperature by 0.2 or 0.3°C every stage, but esophageal and local skin temperature did not change during the first three stages. CVC at the bretylium tosylate-treated site (CVCBT) and sweat expulsion number increased at 38 and 40°C compared with 34°C ( P < 0.05); however, CVC at the untreated site did not change. SSNA increased at 40°C ( P < 0.05, different from 34°C). However, SSNA burst amplitude increased ( P < 0.05), whereas SSNA burst duration decreased ( P < 0.05), at the same time as we observed the increase in CVCBT and sweat expulsion number. These data support the hypothesis that the active vasodilator system is activated by changes in mean skin temperature, even at normal core temperature, and illustrate the intricate competition between active vasodilator and the vasoconstrictor system for control of skin blood flow during mild heat stress.

Effect of cold air inhalation on core temperature in exercising subjects under heat stress

1988 ◽  
Vol 64 (6) ◽  
pp. 2381-2387 ◽  
Author(s):  
N. Geladas ◽  
E. W. Banister
Keyword(s):  
Heat Stress ◽  
Skin Temperature ◽  
Core Temperature ◽  
Random Sequence ◽  
Ambient Air ◽  
Fluid Loss ◽  
Physical Conditioning ◽  
Upper Airways ◽  
Cold Air ◽  
Hot Air

Whether increasing respiratory heat loss (RHL) during exercise under heat stress can contain elevation of rectal temperature (Tre) was examined. Eight men cycled twice at 45–50% their maximum work rate until exhaustion at ambient temperature and relative humidity of 38 degrees C and 90–95%, respectively. They inspired either cold (3.6 degrees C) or ambient air in random sequence. When subjects breathed cold air during 23 min of exercise, a ninefold increase in RHL was observed vs. similar work during hot air inhalation (32.81 vs. 3.46 W). Respiratory frequency (f) and rate of rise in Tre decreased significantly (P less than or equal to 0.004 and P less than or equal to 0.002, respectively). The rise in skin temperature in each inhalant gas condition was accompanied by a parallel almost equal increase in core temperature above basal (delta Tre) for equivalent gains in skin temperature. The increase in tidal volume and decreased f in the cold condition allowed more effective physical conditioning of cold inspirate gas in the upper airways and aided RHL. Cold air inhalation also produced a significant (P less than or equal to 0.05) decrease in heart rate vs. hot air inhalation in the final stages of exercise. Insignificant changes in O2 consumption and total body fluid loss were found. These data show that cold air inhalation during exercise diminishes elevation of Tre and suggest that both the intensity and duration of work can thus be extended. The importance of the physical exchange of heat energy and any physiological mechanisms induced by the cold inspirate in producing the changes is undetermined.

Heat stress and thermal dehydration: lactacidemia and plasma volume regulation

1991 ◽  
Vol 71 (6) ◽  
pp. 2434-2439 ◽  
Author(s):  
Y. Zurovski ◽  
L. Eckstein ◽  
M. Horowitz
Keyword(s):  
Heat Stress ◽  
Plasma Protein ◽  
Plasma Volume ◽  
Significant Rise ◽  
Thermal Dehydration ◽  
Fluid Loss ◽  
Temperature Threshold ◽  
Laboratory Rats ◽  
Before And After ◽  
A Minor

This investigation was undertaken to study heat stress and dehydration effects on 1) plasma lactic acid (LA) concentration and 2) plasma LA effect on plasma volume conservation during thermal dehydration. Experiments were performed on conscious nonacclimated and heat-acclimated laboratory rats subjected to various levels of heat stress and/or dehydration (37–42 degrees C with and without drinking water). During the exposures, rectal temperature (Tre), plasma LA pyruvic acids, and hematocrit were measured. From these data, excess LA, indicative of anaerobic metabolism, was calculated. In separate experiments, transvascular protein efflux (half time of Evans blue-labeled albumin) was measured before and after plasma LA elevation, either by LA infusion or thermal dehydration. The results show that elevation of plasma LA was associated with a rise in Tre, with accelerated elevation within a Tre range of 41–42 degrees C. LA concentrations were similar for the same Tre in all experimental groups. In nonacclimated rats, this rise was accompanied by a significant rise in excess LA. In acclimated rats, only a minor rise in excess LA was observed. A positive correlation was found between plasma LA elevation and the increase in plasma protein efflux. It is concluded that there is a temperature threshold for the rise in plasma LA. In nonacclimated rats, local hypoxia may contribute to this rise. The data also suggest that, in nonacclimated rats, lactacidemia accelerates plasma protein and fluid loss, leading to circulatory failure during acute thermal dehydration.

Effect of heat stress on cutaneous vascular responses to the initiation of exercise

1982 ◽  
Vol 53 (3) ◽  
pp. 744-749 ◽  
Author(s):  
J. M. Johnson ◽  
M. K. Park
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Temperature ◽  
Skin Blood Flow ◽  
Forearm Blood Flow ◽  
Moderate Intensity ◽  
Internal Temperature ◽  
Vascular Responses ◽  
Vasoconstrictor Response ◽  
Leg Exercise

To explore further the competition between vasoconstrictor and vasodilator reflexes in the regulation of skin blood flow, responses in forearm blood flow (FBF) to the initiation of supine leg exercise were measured by plethysmography against a background of rising internal temperature. In 17 studies involving six men, skin temperature (Tsk) was controlled with water-perfused suits first at normothermic levels, followed by a 40- to 50-min period during which Tsk was held at 3813;38.5 degrees C. Supine leg exercise at a moderate intensity (100–150 W) was performed for 5–6 min of each 15 min throughout, yielding one period of exercise performed during normothermic conditions and three periods of exercise performed during the period of elevated Tsk. On the average, FBF fell significantly with the beginning of each period of exercise (P less than 0.05). Furthermore, the amount by which FBF fell tended to increase with increasing levels of preexercise FBF. Thus the average fall in FBF associated with the onset of the last period of exercise, 2.45 ml X 100 ml-1 X min-1, significantly exceeded the 1.12 ml X 100 ml-1 X min-1 fall in FBF seen with onset of work in normothermic conditions. These responses were not due to changes in internal temperature as reflected by esophageal temperatures. However, individual studies occasionally revealed a reduction or abolition of the vasoconstrictor response with the last period of exercise. These findings are in agreement with earlier studies showing a cutaneous participation in the vasoconstrictor responses to exercise but also indicate that sufficient hyperthermia can attenuate or even abolish this response.

Changes in plasma volume, in transcapillary escape rate of albumin and in subcutaneous blood flow during hypoglycaemia in man

1985 ◽  
Vol 69 (3) ◽  
pp. 273-277 ◽  
Author(s):  
J. Hilsted ◽  
F. Bonde-Petersen ◽  
S. Madsbad ◽  
H.-H. Parving ◽  
N. J. Christensen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Skin Temperature ◽  
Plasma Volume ◽  
Escape Rate ◽  
Tissue Blood Flow ◽  
Simple Relationship ◽  
Young Males ◽  
Transcapillary Escape Rate ◽  
Subcutaneous Blood Flow ◽  
Subcutaneous Adipose

1. Hypoglycaemia was induced by insulin injected intravenously (0.15 i.u./kg body weight) in seven healthy young males. 2. Plasma volume was measured before and during hypoglycaemia by intravenous injection of 125I before hypoglycaemia and of 131I during hypoglycaemia. Plasma volume decreased and transcapillary escape rate increased significantly during hypoglycaemia. 3. Skin temperature and local subcutaneous adipose tissue blood flow were measured in four different regions. Both tended to decrease during hypoglycaemia and decreased significantly 2 h after hypoglycaemia. There was no correlation between changes in the two measurements, suggesting that there is no simple relationship between subcutaneous blood flow and skin temperature during hypoglycaemia.

scholarly journals Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Steady-State Blood Flow in Microtubes

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 367
Author(s):  
Konstantinos Giannokostas ◽  
Yannis Dimakopoulos ◽  
Andreas Anayiotos ◽  
John Tsamopoulos
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Constitutive Model ◽  
Blood Plasma ◽  
Constitutive Modeling ◽  
Flow Direction ◽  
Momentum Balance ◽  
Plastic Behavior ◽  
Flow Investigation ◽  
The Impact

The present work focuses on the in-silico investigation of the steady-state blood flow in straight microtubes, incorporating advanced constitutive modeling for human blood and blood plasma. The blood constitutive model accounts for the interplay between thixotropy and elasto-visco-plasticity via a scalar variable that describes the level of the local blood structure at any instance. The constitutive model is enhanced by the non-Newtonian modeling of the plasma phase, which features bulk viscoelasticity. Incorporating microcirculation phenomena such as the cell-free layer (CFL) formation or the Fåhraeus and the Fåhraeus-Lindqvist effects is an indispensable part of the blood flow investigation. The coupling between them and the momentum balance is achieved through correlations based on experimental observations. Notably, we propose a new simplified form for the dependence of the apparent viscosity on the hematocrit that predicts the CFL thickness correctly. Our investigation focuses on the impact of the microtube diameter and the pressure-gradient on velocity profiles, normal and shear viscoelastic stresses, and thixotropic properties. We demonstrate the microstructural configuration of blood in steady-state conditions, revealing that blood is highly aggregated in narrow tubes, promoting a flat velocity profile. Additionally, the proper accounting of the CFL thickness shows that for narrow microtubes, the reduction of discharged hematocrit is significant, which in some cases is up to 70%. At high pressure-gradients, the plasmatic proteins in both regions are extended in the flow direction, developing large axial normal stresses, which are more significant in the core region. We also provide normal stress predictions at both the blood/plasma interface (INS) and the tube wall (WNS), which are difficult to measure experimentally. Both decrease with the tube radius; however, they exhibit significant differences in magnitude and type of variation. INS varies linearly from 4.5 to 2 Pa, while WNS exhibits an exponential decrease taking values from 50 mPa to zero.

Acute exercise and cognition: A review with testable questions for future research into cognitive enhancement with blood flow restriction

2021 ◽  
Vol 151 ◽  
pp. 110586
Author(s):  
Yujiro Yamada ◽  
Emily M. Frith ◽  
Vickie Wong ◽  
Robert W. Spitz ◽  
Zachary W. Bell ◽  
...  
Keyword(s):  
Blood Flow ◽  
Acute Exercise ◽  
Cognitive Enhancement ◽  
Blood Flow Restriction ◽  
Future Research ◽  
Flow Restriction

scholarly journals Is there a role for selective vasodilation in the management of sickle cell disease?

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 597-602 ◽  
Author(s):  
GP Rodgers ◽  
MS Roy ◽  
CT Noguchi ◽  
AN Schechter
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Microvascular Obstruction ◽  
Controlled Study ◽  
Control Group ◽  
Cell Disease ◽  
Retinal Arteriolar

Abstract To test the hypothesis that microvascular obstruction to blood flow at the level of the arteriole may be significant in individuals with sickle cell anemia, the ophthalmologic effects of orally administered nifedipine were monitored in 11 steady-state patients. Three patients with evidence of acute peripheral retinal arteriolar occlusion displayed a prompt reperfusion of the involved segment. Two other patients showed fading of retroequatorial red retinal lesions. Color vision performance was improved in six of the nine patients tested. The majority of patients also demonstrated a significant decrease in the amount of blanching of the conjunctiva which reflects improved blood flow to this frequently involved area. Such improvements were not observable in a control group of untreated stable sickle cell subjects. These findings support the hypothesis that inappropriate vasoconstriction or frank vasospasm may be a significant factor in the pathogenesis of the microvascular lesions of sickle cell disease and, further, that selective microvascular entrapment inhibition may offer an additional strategy to the management of this disorder. We believe a larger, placebo-controlled study with nifedipine and similar agents is warranted.

Real-time RT-PCR analysis of housekeeping genes in human skeletal muscle following acute exercise

2004 ◽  
Vol 18 (2) ◽  
pp. 226-231 ◽  
Author(s):  
Douglas J. Mahoney ◽  
Kate Carey ◽  
Ming-Hua Fu ◽  
Rodney Snow ◽  
David Cameron-Smith ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Real Time ◽  
Healthy Subjects ◽  
Acute Exercise ◽  
Housekeeping Genes ◽  
Housekeeping Gene ◽  
Cycle Ergometry ◽  
Pcr Analysis ◽  
28S Rrna ◽  
Rt Pcr

Studies examining gene expression with RT-PCR typically normalize their mRNA data to a constitutively expressed housekeeping gene. The validity of a particular housekeeping gene must be determined for each experimental intervention. We examined the expression of various housekeeping genes following an acute bout of endurance (END) or resistance (RES) exercise. Twenty-four healthy subjects performed either a interval-type cycle ergometry workout to exhaustion (∼75 min; END) or 300 single-leg eccentric contractions (RES). Muscle biopsies were taken before exercise and 3 h and 48 h following exercise. Real-time RT-PCR was performed on β-actin, cyclophilin (CYC), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and β2-microglobulin (β2M). In a second study, 10 healthy subjects performed 90 min of cycle ergometry at ∼65% of V̇o2 max, and we examined a fifth housekeeping gene, 28S rRNA, and reexamined β2M, from muscle biopsy samples taken immediately postexercise. We showed that CYC increased 48 h following both END and RES exercise (3- and 5-fold, respectively; P < 0.01), and 28S rRNA increased immediately following END exercise (2-fold; P = 0.02). β-Actin trended toward an increase following END exercise (1.85-fold collapsed across time; P = 0.13), and GAPDH trended toward a small yet robust increase at 3 h following RES exercise (1.4-fold; P = 0.067). In contrast, β2M was not altered at any time point postexercise. We conclude that β2M and β-actin are the most stably expressed housekeeping genes in skeletal muscle following RES exercise, whereas β2M and GAPDH are the most stably expressed following END exercise.

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