Amano T, Fujii N, Kenny GP, Okamoto Y, Inoue Y, Kondo N. Effects of TEA-sensitive K
+ channel blockade on cholinergic and thermal sweating in endurance trained and untrained men.
Exp Physiol 2022;
107:441-449. [PMID:
35340063 DOI:
10.1113/ep090251]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/23/2022] [Indexed: 11/08/2022]
Abstract
NEW & NOTEWORTHY
What is the central question of this study? Does inhibition of K+ channels modulate the exercise-training-induced augmentation in cholinergic and thermal sweating? What is the main finding and its importance? Iontophoretic administration of tetraethylammonium, a K+ channel blocker, blunted sweating induced by a low dose (0.001%) of cholinergic agent pilocarpine, but not heat-induced sweating. However, no differences in the cholinergic sweating were observed between young endurance trained and untrained men. Thus, while K+ channels play a role in the regulation of eccrine sweating, they do not contribute to the increase in sweating commonly observed in endurance trained adults. Our findings provide important new insights into the mechanisms underlying the regulation of sweating by endurance conditioning.
ABSTRACT
We evaluated the hypothesis that the activation of K+ channels mediate the exercise-training-induced augmentation in cholinergic and thermal sweating. On separate days, 11 endurance trained and 10 untrained men participated in two experimental protocols. Prior to each protocol, we administered 2% tetraethylammonium (TEA, K+ channels blocker) and saline (Control) at forearm skin sites on both arms via transdermal iontophoresis. In protocol 1, a low (0.001%) and high (1%) doses of pilocarpine was administered at the TEA-treated and Control sites over a 60-min period. In protocol 2, participants were passively heated by immersing their lower limbs in hot water (43°C) until core (rectal) temperature (Tco ) increased by 0.8°C above resting levels. Administration of TEA attenuated cholinergic sweating (P = 0.001) during the initial 20-min after the treatment of low dose of pilocarpine only whilst the response was similar between the groups (P = 0.163). Cholinergic and thermal sweating were higher in trained relative to the untrained men (all P≤0.033). Thermal sweating reached ∼90% of the response at a Tco elevation of 0.8°C during initial 20-min of passive heating, which corresponds to the period wherein TEA attenuated cholinergic sweating in protocol 1. However, sweating did not differ between the Control and TEA sites in either group (P = 0.704). We showed that activation of K+ channels does not appear to mediate the elevated sweating response induced by a low dose of pilocarpine in trained men. We also demonstrated that K+ channels do not contribute to sweating during heat stress in either group. This article is protected by copyright. All rights reserved.
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