AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 1 197-R204, Copyright © 1997 by American Physiological Society

ARTICLES

Osmoregulatory inhibition of thermally induced cutaneous vasodilation in passively heated humans

A. Takamata, K. Nagashima, H. Nose and T. Morimoto
Department of Physiology, Kyoto Prefectural University of Medicine, Japan.

We examined the effect of increased plasma osmolality (P(osm)) on cutaneous vasodilatory response to increased esophageal temperature (T(es)) in passively heated human subjects (n = 6). To modify P(osm), subjects were infused with 0.9, 2, or 3% NaCl infusions (Inf) for 90 min on separate days. Infusion rates were 0.2, 0.15, and 0.125 ml.min-1.kg body wt-1 for 0.9, 2, and 3% Inf, respectively, which produced relatively similar plasma volume expansion. Thirty minutes after the end of infusion, subjects immersed their lower legs in a water bath at 42 degrees C (room temperature 28 degrees C) for 60 min after 10 min of preheating control measurements. Passive heating without infusion (NI) served as time control to account for the effect of volume expansion. P(osm) (mosmol/kgH2O) values at the onset of passive heating were 289.9 +/- 1.4, 292.1 +/- 0.6, 298.7 +/- 0.7, and 305.6 +/- 0.6 after NI, 0.9% Inf, 2% Inf, and 3% Inf, respectively. The increases in T(es) (delta T(es)) at equilibrium during passive heating (mean delta T(es) during 55-60 min) were 0.47 +/- 0.08, 0.59 +/- 0.08, 0.85 +/- 0.13, and 1.09 +/- 0.12 degrees C after NI, 0.9% Inf, 2% Inf, and 3% Inf, respectively, which indicates that T(es) at equilibrium increased linearly as P(osm) increased. delta T(es) required to elicit cutaneous vasodilation (delta T(es) threshold for cutaneous vasodilation) also increased linearly as P(osm) increased as well as the delta T(es) threshold for sweating. The calculated increases in these thresholds per unit rise in P(osm) from regression analysis were 0.044 degree C for the cutaneous vasodilation and 0.034 degree C for sweating. Thus the delta T(es) thresholds for cutaneous vasodilation and sweating are shifted to higher delta T(es) along with the increase in P(osm), and these shifts resulted in the higher increase in T(es) during passive heating.

This article has been cited by other articles:

				M. Konishi, K. Kanosue, M. Kano, A. Kobayashi, and K. Nagashima The median preoptic nucleus is involved in the facilitation of heat-escape/cold-seeking behavior during systemic salt loading in rats Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R150 - R159. [Abstract] [Full Text] [PDF]

				M. Shibasaki, T. E. Wilson, and C. G. Crandall Neural control and mechanisms of eccrine sweating during heat stress and exercise J Appl Physiol, May 1, 2006; 100(5): 1692 - 1701. [Abstract] [Full Text] [PDF]

				H. Mitono, H. Endoh, K. Okazaki, T. Ichinose, S. Masuki, A. Takamata, and H. Nose Acute hypoosmolality attenuates the suppression of cutaneous vasodilation with increased exercise intensity J Appl Physiol, September 1, 2005; 99(3): 902 - 908. [Abstract] [Full Text] [PDF]

				T. Ito, T. Itoh, T. Hayano, K. Yamauchi, and A. Takamata Plasma hyperosmolality augments peripheral vascular response to baroreceptor unloading during heat stress Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2005; 289(2): R432 - R440. [Abstract] [Full Text] [PDF]

				T. Ichinose, K. Okazaki, S. Masuki, H. Mitono, M. Chen, H. Endoh, and H. Nose Ten-day endurance training attenuates the hyperosmotic suppression of cutaneous vasodilation during exercise but not sweating J Appl Physiol, July 1, 2005; 99(1): 237 - 243. [Abstract] [Full Text] [PDF]

				D. G. Whyte and A. K. Johnson Lesions of the anteroventral third ventricle region (AV3V) disrupt cardiovascular responses to an elevation in core temperature Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2005; 288(6): R1783 - R1790. [Abstract] [Full Text] [PDF]

				M. Shibasaki, T. E. Wilson, J. Cui, B. D. Levine, and C. G. Crandall Exercise throughout 6{degrees} head-down tilt bed rest preserves thermoregulatory responses J Appl Physiol, November 1, 2003; 95(5): 1817 - 1823. [Abstract] [Full Text] [PDF]

				K. Nagashima, S. Nakai, M. Konishi, L. Su, and K. Kanosue Increased heat-escape/cold-seeking behavior following hypertonic saline injection in rats Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2001; 280(4): R1031 - R1036. [Abstract] [Full Text] [PDF]

				A. Takamata, T. Yoshida, N. Nishida, and T. Morimoto Relationship of osmotic inhibition in thermoregulatory responses and sweat sodium concentration in humans Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2001; 280(3): R623 - R629. [Abstract] [Full Text] [PDF]

				O. Shido, N. Sugimoto, M. Tanabe, and S. Sakurada Core temperature and sweating onset in humans acclimated to heat given at a fixed daily time Am J Physiol Regulatory Integrative Comp Physiol, April 1, 1999; 276(4): R1095 - R1101. [Abstract] [Full Text] [PDF]

				Y. Nakajima, H. Nose, and A. Takamata Plasma hyperosmolality and arterial pressure regulation during heating in dehydrated and awake rats Am J Physiol Regulatory Integrative Comp Physiol, November 1, 1998; 275(5): R1703 - R1711. [Abstract] [Full Text] [PDF]

				A. Takamata, K. Nagashima, H. Nose, and T. Morimoto Role of plasma osmolality in the delayed onset of thermal cutaneous vasodilation during exercise in humans Am J Physiol Regulatory Integrative Comp Physiol, July 1, 1998; 275(1): R286 - R290. [Abstract] [Full Text] [PDF]