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Title: Effects of drinking on thirst and vasopressin in dehydrated elderly men.
Austin Authors: Phillips, P A;Bretherton, M;Risvanis, John;Casley, David J;Johnston, Colin I;Gray, L
Affiliation: Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia
Issue Date: 1-May-1993
Publication information: The American Journal of Physiology; 264(5 Pt 2): R877-81
Abstract: Inhibition of dehydration-induced arginine vasopressin (AVP) secretion and thirst depends on removal of osmotic and hemodynamic stimuli as well as on preabsorptive oropharyngeal factors that reduce thirst and AVP secretion on drinking before correction of the water deficits. Plasma atrial natriuretic peptide (ANP) levels may also change with drinking. Therefore, the thirst and plasma responses to oral water loads (10 ml/kg) in 10 healthy old (64-76 yr) and young (20-32 yr) 24-h water-deprived men were investigated. After 24-h water deprivation plasma sodium, osmolality, and AVP were increased similarly in both groups (P < 0.001). Plasma ANP levels fell after dehydration similarly in both groups (P < 0.05) but were always higher in the older group (P < 0.05). However, although thirst increased in both groups (P < 0.05), this was significantly less in the elderly (P < 0.05). After the water load, thirst was reduced in both groups throughout the study (P < 0.05). However, plasma AVP fell immediately after drinking only in the young group and rose to postdeprivation levels after 15 min. Plasma AVP was not different from postdeprivation throughout in the old group and after 15 min in the young group presumably because the water load was insufficient to replace their water deficits. In the young group only, plasma ANP rose to 182 +/- 43% of postdeprivation levels at 3 min after drinking (P < 0.05). These results demonstrate reduced oropharyngeal inhibition of AVP secretion after drinking in healthy elderly men but maintained inhibition of thirst.
Gov't Doc #: 8498597
Type: Journal Article
Subjects: Adult
Arginine Vasopressin.blood
Atrial Natriuretic Factor.blood
Middle Aged
Osmolar Concentration
Appears in Collections:Journal articles

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