Effect of plasma prolactin on sweat rate and sweat composition during exercise in men.
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)
Physical Education Department, Université de Montréal, Quebec, Canada.
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Boisvert
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Brisson
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Péronnet
D000328:Adult; D000450:Aldosterone / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood; D001971:Bromocriptine / Q000494:pharmacology; D004573:Electrolytes / Q000032:analysis; D015444:Exercise; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D011388:Prolactin / Q000097:blood*; D012083:Renin / Q000097:blood; D013542:Sweat / Q000737:chemistry*; D013546:Sweating / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D004573:Electrolytes; D001971:Bromocriptine; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D011388:Prolactin; D012083:Renin