1. GH and IGF-1 in skin interstitial fluid and blood are associated with heat loss responses in exercising young adults.
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Maimaituxun, Gulinu, Amano, Tatsuro, Kenny, Glen P., Mündel, Toby, Kajiki, Masanobu, Tagawa, Kaname, Katagiri, Akira, Tanabe, Yoko, Watanabe, Koichi, Nishiyasu, Takeshi, Kondo, Narihiko, and Fujii, Naoto
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SOMATOMEDIN C ,EXTRACELLULAR fluid ,SWEAT glands ,YOUNG adults ,HEAT losses - Abstract
Purpose: Sweat glands and cutaneous vessels possess growth hormone (GH) and insulin-like growth factor 1 (IGF-1) receptors. Here, we assessed if exercise increases GH and IGF-1 in skin interstitial fluid, and whether baseline and exercise-induced increases in GH and IGF-1 concentrations in skin interstitial fluid/blood are associated with heat loss responses of sweating and cutaneous vasodilation. Methods: Sixteen young adults (7 women) performed a 50-min moderate-intensity exercise bout (50% VO
2peak ) during which skin dialysate and blood samples were collected. In a sub-study (n = 7, 4 women), we administered varying concentrations of GH (0.025–4000 ng/mL) and IGF-1 (0.000256–100 µg/mL) into skin interstitial fluid via intradermal microdialysis. Sweat rate (ventilated capsule) and cutaneous vascular conductance (CVC) were measured continuously for both studies. Results: Exercise increased sweating and CVC (both P < 0.001), paralleled by increases of serum GH and skin dialysate GH and IGF-1 (all P ≤ 0.041) without changes in serum IGF-1. Sweating was positively correlated with baseline dialysate and serum GH levels, as well as exercise-induced increases in serum GH and IGF-1 (all P ≤ 0.044). Increases in CVC were not correlated with any GH and IGF-1 variables. Exogenous administration of GH and IGF-1 did not modulate resting sweat rate and CVC. Conclusion: (1) Exercise increases GH and IGF-1 levels in the skin interstitial fluid, (2) exercise-induced sweating is associated with baseline GH in skin interstitial fluid and blood, as well as exercise-induced increases in blood GH and IGF-1, and (3) cutaneous vasodilation during exercise is not associated with GH and IGF-1 in skin interstitial fluid and blood. [ABSTRACT FROM AUTHOR]- Published
- 2024
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