Relationship of osmotic inhibition in thermoregulatory responses and sweat sodium concentration in humans
1 Department of Physiology and 2 College of Medical Technology, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602 - 0841, Japan Heat acclimatization improves thermoregulatory responses to heat stress and decreases sweat sodium concentration ([Na + ] sweat ). The reduced [Na + ] sweat...
Saved in:
Published in | American journal of physiology. Regulatory, integrative and comparative physiology Vol. 280; no. 3; pp. 623 - R629 |
---|---|
Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
01.03.2001
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | 1 Department of Physiology and 2 College of Medical
Technology, Kyoto Prefectural University of Medicine, Kamigyo-ku,
Kyoto 602 - 0841, Japan
Heat acclimatization
improves thermoregulatory responses to heat stress and decreases sweat
sodium concentration ([Na + ] sweat ). The
reduced [Na + ] sweat results in a larger
increase in plasma osmolality (P osmol ) at a given amount of
sweat output. The increase in P osmol inhibits thermoregulatory responses to increased body core temperature. Therefore, we hypothesized that the inhibitory effect of plasma hyperosmolality on the thermoregulatory responses to heat stress should
be attenuated with the reduction of
[Na + ] sweat due to heat acclimatization.
Eleven subjects (9 male and 2 female) were passively heated by
immersing their lower legs into water at 42°C (room temperature
28°C and relative humidity 30%) for 50 min following isotonic or
hypertonic saline infusion. We determined the increase in the
esophageal temperature (T es ) required to elicit sweating
and cutaneous vasodilation (CVD) ( T es thresholds for
sweating and CVD, respectively) in each condition and calculated the
elevation of the T es thresholds per unit increase in
P osmol as the osmotic inhibition of sweating and CVD. The
osmotic shift in the T es thresholds for both sweating
and CVD correlated linearly with [Na + ] sweat
( r = 0.858 and r = 0.628, respectively). Thus subjects with a lower
[Na + ] sweat showed a smaller osmotic elevation
of the T es thresholds for sweating and CVD. These
results suggest the possibility that heat acclimatization attenuates
osmotic inhibition of thermoregulatory responses as well as reducing
[Na + ] sweat .
osmoregulation; sweating; cutaneous vasodilation; plasma
osmolality; vasopressin |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0363-6119 1522-1490 |
DOI: | 10.1152/ajpregu.2001.280.3.r623 |