Plasma hyperosmolality attenuates skin sympathetic nerve activity during passive heat stress in XXXX .

@entity1 @entity8450 @entity8670 @entity4202
UNASSIGNED: In @entity1 , @entity8450 delays the onset of sweating and cutaneous vasodilation during heat stress. However, it remains unknown if hyperosmolality exerts this effect through a central (i.e. central nervous system) and/or peripheral (i.e. effector organ) modulation of thermoregulatory activity. We examined if intravenous infusion of hyperosmotic saline affects skin sympathetic nerve activity (SSNA) during whole-body passive heating in healthy @entity1 . Furthermore, we examined if local intradermal infusion of hyperosmotic saline affects sweating and cutaneous vasodilation during passive heating. Following intravenous infusion of either 0.9% ( @entity8670 ) or 3.0% (HYPER) @entity4202 saline, 12 subjects were passively heated until core temperature increased by    0.6  C. During each condition, sweating and cutaneous vascular conductance were measured over two intradermal microdialysis probes, one perfused with @entity8670 saline and the other with HYPER saline. Intravenous infusion of HYPER saline increased plasma osmolality (294      3 to 316      5 mOsm/kgH2 O, P   <=  0.01), which remained greater than @entity8670 throughout heating. Plasma hyperosmolality delayed the mean body temperature onset of sweating (+1.24      0.18  vs. +1.60      0.18  C, P   <=  0.01) and cutaneous vasodilation (+1.15      0.18  vs. +1.53      0.22  C, P   <=  0.01), and attenuated the increase in SSNA during heating (+147      178  vs. +427      281%, P   <=  0.01). Intradermal infusion of HYPER saline increased baseline CVC (P   <=  0.01), which did not increase further during the subsequent heating period (P  =  0.11). In contrast, intradermal infusion of HYPER saline did not affect sweating (P  =  0.99). These results provide direct evidence that @entity8450 exerts a central modulatory effect governing efferent thermoregulatory activity in @entity1 . This article is protected by copyright. All rights reserved.
