AJP - Renal Physiology, Vol 264, Issue 5 816-F820, Copyright © 1993 by American Physiological Society
Effect of plasma prolactin on sweat rate and sweat composition during exercise in men
P. Boisvert, G. R. Brisson and F. Peronnet
Physical Education Department, Universite de Montreal, Quebec, Canada.
We investigated the role of the exercise-induced elevation of plasma
prolactin (PRL) concentration on sweat rate and composition during
prolonged exercise in men. Two groups of healthy young males (20-26 yr old)
showing a high (high responders; n = 8) or a low (low responders; n = 7)
response of plasma PRL concentration to exercise were studied during a
60-min period of exercise on a cycle ergometer (65% maximum O2 consumption)
in warm conditions (26.2 +/- 0.1 degrees C; 57 +/- 1% relative humidity), 1
h after receiving 1.25 mg bromocriptine (BRC) per os or a placebo. In high
responders, administration of BRC totally abolished the threefold increase
in plasma PRL observed in response to exercise with placebo [placebo, 10
+/- 2 (rest) and 30 +/- 2 micrograms/l (exercise); BRC, 9 +/- 1 (rest) and
8 +/- 1 microgram/l (exercise)]. The latter was associated with a
significant decrease in sweat rate (2.7 +/- 0.5 to 1.9 +/- 0.3
microliter.cm-2.min-1) and a significant increase in sweat Na+
concentration (57 +/- 7 to 68 +/- 5 mmol/l). BRC also reduced the small
response in plasma PRL concentration observed in low responders [placebo,
10 +/- 1 (rest) and 15 +/- 1 microgram/l (exercise); BRC, 9 +/- 1 (rest)
and 7 +/- 1 microgram/l (exercise)], but this was not associated with any
change in sweat rate (2.2 +/- 0.2 to 1.9 +/- 0.3 microliter.cm-2.min-1) or
in sweat Na+ concentration (63 +/- 10 to 64 +/- 9 mmol/l).(ABSTRACT
TRUNCATED AT 250 WORDS)
