Regional influence of nitric oxide on cutaneous vasodilatation and sweating during exercise-heat stress in young men.

NEW FINDINGS: What is the central question of this study? We evaluated whether regional differences exist in nitric oxide synthase (NOS) dependent cutaneous vasodilatation and sweating during exercise-heat stress in young men What is the main finding and its importance? Exercise-induced increases in cutaneous vasodilatation and sweating were greater on the chest and upper back compared to the forearm, although the NOS contribution to cutaneous vasodilatation was similar across all regions. Conversely, there was a greater NOS-dependent rate of change in sweating on the chest compared to the forearm, with a similar trend on the back. ABSTRACT: While it is established that nitric oxide synthase (NOS) is an important modulator of forearm cutaneous vasodilatation and sweating during an exercise-heat stress in young men, it remains unclear if regional differences exist in this response. In fifteen habitually active young men (24 +/- 4 (SD) years), cutaneous vascular conductance (CVC) and local sweat rate (LSR) were assessed at three body regions. On each of the dorsal forearm, chest, and upper-back (trapezius), sites were continuously perfused with either 1) lactated Ringer's (control) or 2) 10 mM N(omega) -nitro-L-arginine (L-NNA, NOS inhibitor), via microdialysis. Participants rested in the heat (35 degrees C) for approximately 75-min, followed by 60-min of semi-recumbent cycling performed at a fixed rate of heat production of 200 W.m(-2) (equivalent to approximately 42% VO2peak ). During exercise, the chest and upper-back regions showed higher CVC and LSR responses relative to the forearm (all P 0.05). Conversely, there was a greater NOS-contribution to the rate of change for LSR at the chest relative to the forearm (P < 0.05) with a similar trend for the back. In habitually active young men, NOS-dependent cutaneous vasodilatation was similar across regions while the NOS-contribution to LSR was greater on the chest relative to the forearm. These findings advance our understanding of the mechanisms influencing regional variations in cutaneous vasodilatation and sweating during an exercise-heat stress. This article is protected by copyright. All rights reserved.