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Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black-African and Caucasian descent during exercise in the heat.
Exp Physiol 2019; 104(12):1762-1768EP

Abstract

NEW FINDINGS

What is the central question of this study? Nitric oxide modulates cutaneous vasodilatation and sweating during exercise-induced heat stress in young men. However, it remains uncertain whether these effects are reduced in black-African descendants, who commonly demonstrate reduced nitric oxide bioavailability. Therefore, we assessed whether black-African descendants display reduced nitric oxide-dependent cutaneous vasodilatation and sweating compared with Caucasians in these conditions. What is the main finding and its importance? Nitric oxide-dependent cutaneous vasodilatation and sweating were similar between groups, indicating that reduced nitric oxide bioavailability in black-African descendants does not attenuate these heat-loss responses during an exercise-induced heat stress.

ABSTRACT

Men of black-African descent are at an increased risk of heat-related illness relative to their Caucasian counterparts. This might be attributable, in part, to reduced cutaneous nitric oxide (NO) bioavailability in this population, which might alter local cutaneous vasodilatation and sweating. To evaluate this, we compared these heat-loss responses in young men (18-30 years of age) of black-African (n = 10) and Caucasian (n = 10) descent during rest, exercise and recovery in the heat. Participants were matched for physical characteristics and fitness, and they were all born and raised in the same temperate environment (i.e. Canada; second generation and higher). Both groups rested for 10 min and then performed 50 min of moderate-intensity exercise at 200 W m-2 , followed by 30 min of recovery in hot, dry heat (35°C, 20% relative humidity). Local cutaneous vascular conductance (CVC%max) and sweat rate (SR) were measured at two forearm skin sites treated with either lactated Ringer solution (control) or 10 mm NG -nitro-l-arginine methyl ester (l-NAME, a nitric oxide (NO) synthase inhibitor). l-NAME significantly reduced CVC%max throughout rest, exercise and recovery in both groups (both P < 0.001). However, there were no significant main effects for the contribution of NO to CVC%max between groups (all P > 0.500). l-NAME significantly reduced local SR in both groups (both P < 0.050). The contribution of NO to SR was similar between groups such that l-NAME reduced SR relative to control at 40 and 50 min into exercise (both P < 0.05). We demonstrate that ethnicity per se does not influence NO-dependent cutaneous vasodilatation and sweating in healthy young men of black-African and Caucasian descent during exercise in dry heat.

Authors+Show Affiliations

Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada. Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan.Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31609035

Citation

Muia, Caroline M., et al. "Contribution of Nitric Oxide Synthase to Cutaneous Vasodilatation and Sweating in Men of black-African and Caucasian Descent During Exercise in the Heat." Experimental Physiology, vol. 104, no. 12, 2019, pp. 1762-1768.
Muia CM, McGarr GW, Schmidt MD, et al. Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black-African and Caucasian descent during exercise in the heat. Exp Physiol. 2019;104(12):1762-1768.
Muia, C. M., McGarr, G. W., Schmidt, M. D., Fujii, N., Amano, T., & Kenny, G. P. (2019). Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black-African and Caucasian descent during exercise in the heat. Experimental Physiology, 104(12), pp. 1762-1768. doi:10.1113/EP088115.
Muia CM, et al. Contribution of Nitric Oxide Synthase to Cutaneous Vasodilatation and Sweating in Men of black-African and Caucasian Descent During Exercise in the Heat. Exp Physiol. 2019;104(12):1762-1768. PubMed PMID: 31609035.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Contribution of nitric oxide synthase to cutaneous vasodilatation and sweating in men of black-African and Caucasian descent during exercise in the heat. AU - Muia,Caroline M, AU - McGarr,Gregory W, AU - Schmidt,Madison D, AU - Fujii,Naoto, AU - Amano,Tatsuro, AU - Kenny,Glen P, Y1 - 2019/11/13/ PY - 2019/08/21/received PY - 2019/10/11/accepted PY - 2019/10/15/pubmed PY - 2019/10/15/medline PY - 2019/10/15/entrez KW - core temperature KW - eccrine sweating KW - ethnicity KW - exercise-induced heat stress KW - heat adaptation KW - heat loss KW - skin blood flow SP - 1762 EP - 1768 JF - Experimental physiology JO - Exp. Physiol. VL - 104 IS - 12 N2 - NEW FINDINGS: What is the central question of this study? Nitric oxide modulates cutaneous vasodilatation and sweating during exercise-induced heat stress in young men. However, it remains uncertain whether these effects are reduced in black-African descendants, who commonly demonstrate reduced nitric oxide bioavailability. Therefore, we assessed whether black-African descendants display reduced nitric oxide-dependent cutaneous vasodilatation and sweating compared with Caucasians in these conditions. What is the main finding and its importance? Nitric oxide-dependent cutaneous vasodilatation and sweating were similar between groups, indicating that reduced nitric oxide bioavailability in black-African descendants does not attenuate these heat-loss responses during an exercise-induced heat stress. ABSTRACT: Men of black-African descent are at an increased risk of heat-related illness relative to their Caucasian counterparts. This might be attributable, in part, to reduced cutaneous nitric oxide (NO) bioavailability in this population, which might alter local cutaneous vasodilatation and sweating. To evaluate this, we compared these heat-loss responses in young men (18-30 years of age) of black-African (n = 10) and Caucasian (n = 10) descent during rest, exercise and recovery in the heat. Participants were matched for physical characteristics and fitness, and they were all born and raised in the same temperate environment (i.e. Canada; second generation and higher). Both groups rested for 10 min and then performed 50 min of moderate-intensity exercise at 200 W m-2 , followed by 30 min of recovery in hot, dry heat (35°C, 20% relative humidity). Local cutaneous vascular conductance (CVC%max) and sweat rate (SR) were measured at two forearm skin sites treated with either lactated Ringer solution (control) or 10 mm NG -nitro-l-arginine methyl ester (l-NAME, a nitric oxide (NO) synthase inhibitor). l-NAME significantly reduced CVC%max throughout rest, exercise and recovery in both groups (both P < 0.001). However, there were no significant main effects for the contribution of NO to CVC%max between groups (all P > 0.500). l-NAME significantly reduced local SR in both groups (both P < 0.050). The contribution of NO to SR was similar between groups such that l-NAME reduced SR relative to control at 40 and 50 min into exercise (both P < 0.05). We demonstrate that ethnicity per se does not influence NO-dependent cutaneous vasodilatation and sweating in healthy young men of black-African and Caucasian descent during exercise in dry heat. SN - 1469-445X UR - https://www.unboundmedicine.com/medline/citation/31609035/Contribution_of_nitric_oxide_synthase_to_cutaneous_vasodilatation_and_sweating_in_men_of_black_African_and_Caucasian_descent_during_exercise_in_the_heat_ L2 - https://doi.org/10.1113/EP088115 DB - PRIME DP - Unbound Medicine ER -