AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 4 762-R764, Copyright © 1989 by American Physiological Society
Dependent effect of drinking volume on vasopressin but not atrial peptide in humans
T. D. Williams, J. R. Seckl and S. L. Lightman
Department of Medicine, Charing Cross and Westminster Medical School, Westminster Hospital, London, United Kingdom.
The act of drinking causes a fall in plasma arginine vasopressin (AVP)
concentration that precedes changes in plasma osmolality. To investigate
the specificity of this drinking stimulus on hormone secretion, six
volunteers (5 male, 1 female, aged 22-39 yr) were water deprived for 36 h
and then drank 15 ml/kg water at 10-12 degrees C using 15-20 swallowing
actions/min over 3.5 +/- 0.5 min (mean +/- SE). This caused a fall in
plasma AVP from 4.5 +/- 0.7 to 3.2 +/- 0.5 pmol/l (P less than 0.05) and in
thirst (by 5.7 +/- 0.6 on a 10-cm linear analog scale) (P less than 0.05) 5
min after drinking. No significant changes occurred in mean arterial
pressure, heart rate, or plasma atrial natriuretic peptide (ANP)
concentration. A second study was undertaken to determine whether the
reflex inhibition of AVP secretion is activated simply by the act of
swallowing regardless of the volume of liquid consumed. The six volunteers
were water deprived for 36 h and then sipped and swallowed 1 ml/kg water at
10-12 degrees C using 15-20 swallowing actions/min over 3.0 +/- 0.1 min.
There was no change in plasma AVP concentration, although thirst was
reduced by 2.3 +/- 0.6 (P less than 0.05) at 5 min. Plasma AVP 10 min after
sipping and swallowing (4.2 +/- 0.8 pmol/l) was significantly greater than
at 10 min after drinking 15 ml/kg (2.8 +/- 0.5 pmol/l) (P less than 0.05)
despite the fact that plasma osmolality at this stage was similar in both
studies. We conclude that the drinking-mediated reflex inhibition of AVP
secretion in humans is dependent on swallowing an adequate volume and is
not accompanied by changes in hemodynamics or in plasma ANP concentration.
