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Mechanism of attenuated thirst in aging: role of central volume receptors.
Am J Physiol. 1997 Jan; 272(1 Pt 2):R148-57.AJ

Abstract

To test the hypothesis that the inhibitory action of central blood volume expansion on thirst and renal fluid regulation is attenuated with aging, we monitored the drinking and renal responses of dehydrated older (70 +/- 2 yr, n = 6) and younger (24 +/- 1 yr, n = 6) subjects during 195 min of head-out water immersion (HOI), which shifts blood centrally and increases plasma volume (PV). Subjects dehydrated by exercising for 2 h at 36 degrees C in the evening and refraining from fluids overnight before HOI in 34 degrees C water or a seated control in water perfusion suit [time control (TC)] the next morning. Ad libitum water intake was allowed after 15 min of HOI. Dehydration decreased PV by 10.6 +/- 1 and 7.3 +/- 1.8% (P < 0.05) and increased plasma osmolality by 6 +/- 2 and 7 +/- 1 mosmol/kg H2O (P < 0.05) in older and younger subjects, respectively. Thirst ratings increased in both groups, but pre-HOI thirst perception on a line rating scale was lower in older (69 +/- 8 mm) than younger (94 +/- 6 mm, P < 0.05) subjects. Fifteen minutes of HOI restored PV by 7.8 +/- 1.0 and 5.7 +/- 1.0% in older and younger subjects, respectively, but suppressed thirst rating in younger subjects only (P < 0.05). Fluid intake was reduced in HOI compared with TC in younger (6.3 +/- 0.5 vs. 14.3 +/- 2.2 ml/kg, P < 0.05) but not in older (6.7 +/- 2.1 vs. 8.4 +/- 3.3 ml/kg) subjects. During HOI, older subjects had smaller suppression of plasma renin activity and aldosterone concentration but a greater increase in the plasma atrial natriuretic peptide concentration (P[ANP], P < 0.05). HOI increased fractional sodium excretion in both groups, but mean arterial pressure increased only in the older subjects (P < 0.05). We conclude that the inhibitory influence of central volume expansion on thirst and drinking behavior is diminished with aging. Furthermore, in contrast to younger people, HOI natriuresis is associated with exaggerated increases in P[ANP] and arterial blood pressure in older people, suggesting arterial baroreceptors may be involved in the fluid regulatory response to central blood volume expansion in older people.

Authors+Show Affiliations

John B. Pierce Laboratory, Yale University School of Medicine, New Haven, Connecticut 06519, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9039003

Citation

Stachenfeld, N S., et al. "Mechanism of Attenuated Thirst in Aging: Role of Central Volume Receptors." The American Journal of Physiology, vol. 272, no. 1 Pt 2, 1997, pp. R148-57.
Stachenfeld NS, DiPietro L, Nadel ER, et al. Mechanism of attenuated thirst in aging: role of central volume receptors. Am J Physiol. 1997;272(1 Pt 2):R148-57.
Stachenfeld, N. S., DiPietro, L., Nadel, E. R., & Mack, G. W. (1997). Mechanism of attenuated thirst in aging: role of central volume receptors. The American Journal of Physiology, 272(1 Pt 2), R148-57.
Stachenfeld NS, et al. Mechanism of Attenuated Thirst in Aging: Role of Central Volume Receptors. Am J Physiol. 1997;272(1 Pt 2):R148-57. PubMed PMID: 9039003.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mechanism of attenuated thirst in aging: role of central volume receptors. AU - Stachenfeld,N S, AU - DiPietro,L, AU - Nadel,E R, AU - Mack,G W, PY - 1997/1/1/pubmed PY - 1997/1/1/medline PY - 1997/1/1/entrez KW - Non-programmatic SP - R148 EP - 57 JF - The American journal of physiology JO - Am. J. Physiol. VL - 272 IS - 1 Pt 2 N2 - To test the hypothesis that the inhibitory action of central blood volume expansion on thirst and renal fluid regulation is attenuated with aging, we monitored the drinking and renal responses of dehydrated older (70 +/- 2 yr, n = 6) and younger (24 +/- 1 yr, n = 6) subjects during 195 min of head-out water immersion (HOI), which shifts blood centrally and increases plasma volume (PV). Subjects dehydrated by exercising for 2 h at 36 degrees C in the evening and refraining from fluids overnight before HOI in 34 degrees C water or a seated control in water perfusion suit [time control (TC)] the next morning. Ad libitum water intake was allowed after 15 min of HOI. Dehydration decreased PV by 10.6 +/- 1 and 7.3 +/- 1.8% (P < 0.05) and increased plasma osmolality by 6 +/- 2 and 7 +/- 1 mosmol/kg H2O (P < 0.05) in older and younger subjects, respectively. Thirst ratings increased in both groups, but pre-HOI thirst perception on a line rating scale was lower in older (69 +/- 8 mm) than younger (94 +/- 6 mm, P < 0.05) subjects. Fifteen minutes of HOI restored PV by 7.8 +/- 1.0 and 5.7 +/- 1.0% in older and younger subjects, respectively, but suppressed thirst rating in younger subjects only (P < 0.05). Fluid intake was reduced in HOI compared with TC in younger (6.3 +/- 0.5 vs. 14.3 +/- 2.2 ml/kg, P < 0.05) but not in older (6.7 +/- 2.1 vs. 8.4 +/- 3.3 ml/kg) subjects. During HOI, older subjects had smaller suppression of plasma renin activity and aldosterone concentration but a greater increase in the plasma atrial natriuretic peptide concentration (P[ANP], P < 0.05). HOI increased fractional sodium excretion in both groups, but mean arterial pressure increased only in the older subjects (P < 0.05). We conclude that the inhibitory influence of central volume expansion on thirst and drinking behavior is diminished with aging. Furthermore, in contrast to younger people, HOI natriuresis is associated with exaggerated increases in P[ANP] and arterial blood pressure in older people, suggesting arterial baroreceptors may be involved in the fluid regulatory response to central blood volume expansion in older people. SN - 0002-9513 UR - https://www.unboundmedicine.com/medline/citation/9039003/Mechanism_of_attenuated_thirst_in_aging:_role_of_central_volume_receptors_ L2 - http://journals.physiology.org/doi/full/10.1152/ajpregu.1997.272.1.R148?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -