Effects of drinking on thirst and vasopressin in dehydrated elderly men

Phillips, Paddy A.; Bretherton, M; Risvanis, John; Casley, David; Johnston, Colin I.; Gray, Laura J.

doi:10.1152/ajpregu.1993.264.5.r877

Cited by 39 publications

(49 citation statements)

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“…However, the relation between thirst and the rate of fluid intake was maintained in the elderly. These are identical to the results reported by Phillips et al 75) reported that thirst sensation after 24-h water deprivation was attenuated in the elderly. Moreover, there have been several studies suggesting that sodium retention mechanisms are reduced in the elderly; higher [Na + ] sweat due to impairment of the salt reabsorptive ability of sweat gland ducts 69) and the decrease in renal concentrating ability in aging rats due to the impaired responsiveness of the kidney to AVP 76) .…”

Section: Impaired Thermoregulatory and Body Fluid Regulationssupporting

confidence: 92%

Heat Illness during Working and Preventive Considerations from Body Fluid Homeostasis

Kamijo

Nosé

2006

Ind Health

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The purposes of this review are to show pathophysiological mechanisms for heat illness during working in a hot environment and accordingly provide some preventive considerations from a viewpoint of body fluid homeostasis. The incidence of the heat illness is closely associated with body temperature regulation, which is much affected by body fluid state in humans. Heat generated by contracting muscles during working increases body temperature, which, in a feedback manner, drives heat-dissipation mechanisms of skin blood flow and sweating to prevent a rise in body temperature. However, the impairment of heat-dissipation mechanisms caused by hard work in hot, humid, and dehydrated conditions accelerates the increase in body temperature, and, if not properly treated, leads to heat illness. First, we overviewed thermoregulation during working (exercising) in a hot environment, describe the effects of dehydration on skin blood flow and sweating, and then explained how they contributes to the progression toward heat illness. Second, we described the advantageous effects of blood volume expansion after heat acclimatization on temperature regulation during exercise as well as those of restitution from dehydration by supplementation of carbohydrate-electrolyte solution. Finally, we described that the deteriorated thermoregulation in the elderly is closely associated with the impaired body fluid regulation and that blood volume expansion by exercise training with protein supplementation improves thermoregulation.

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Section: Impaired Thermoregulatory and Body Fluid Regulationssupporting

confidence: 92%

Heat Illness during Working and Preventive Considerations from Body Fluid Homeostasis

Kamijo

Nosé

2006

Ind Health

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“…To our knowledge, increased tubular reabsorption in the elderly has not been reported. The association of higher plasma urea levels and lower FE urea values in the elderly could reflect a preservation of the tubular effect of vasopressin on urea reabsorption, which possibly differs from the widely known age-related decrease in water reabsorption in the elderly (19 -21), despite an enhanced osmoreceptor sensitivity to vasopressin release (7,22) and higher vasopressin levels (7,(23)(24)(25). In rats, age-associated defects in urine concentration are accompanied by a downregulation of renal vasopressin V 2 receptors and aquaporin-2 expression (26).…”

Section: Discussionmentioning

confidence: 93%

Age-Related Increase in Plasma Urea Level and Decrease in Fractional Urea Excretion

Musch

Verfaillie

Decaux

2006

Clinical Journal of the American Society of Nephrology

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This study confirms in humans an age-related increase in plasma urea levels (r ‫؍‬ 0.62; P < 0.001; y ‫؍‬ 0.229x ؉ 18.26) and no correlation between plasma creatinine and age (r ‫؍‬ 0.06; NS). Fractional urea excretion (FE urea) decreases with age (r ‫؍‬ ؊0.41; P < 0.001; y ‫؍‬ ؊0.226x ؉ 55). Comparing urea and creatinine clearances, measured in 19 young and in 15 old women, a larger decrease of urea clearance (؊56%) compared with the creatinine clearance (؊43%) was observed as expected, explaining the lower FE urea in the elderly. In old women, the daily urea excretion was 27% and the daily creatinine excretion was 42% lower than in young women. An age-related decrease of same magnitude in both creatinine production and creatinine clearance explains why plasma creatinine remains stable with increasing age. The observation of a more important decrease in urea clearance (56%) than in urea production (27%) in older women led to an expected increase in plasma urea of 29%. These observations incited a comparison of biochemical profiles from younger and older patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Young patients with SIADH present lower mean plasma urea (18 ؎ 8 mg/dl) and higher mean FE urea (58 ؎ 14%), compared with both young control subjects (mean plasma urea 27 ؎ 7 mg/dl; mean FE urea 46 ؎ 10%) and old patients with SIADH (mean plasma urea 29 ؎ 8 mg/dl; mean FE urea 44 ؎ 15%). Physicians must realize that frankly low plasma urea values and high FE urea values can be expected only in young patients with SIADH, whereas old patients with SIADH will present values of plasma urea and FE urea in the same range than young control subjects. However, old patients with SIADH show still lower mean plasma urea values and higher mean FE urea values, compared with old control subjects (mean plasma urea 39 ؎ 8 mg/dl; mean FE urea 36 ؎ 9%), in whom plasma urea values between 40 and 50 mg/dl must be considered as usual.Clin J Am Soc Nephrol 1: 909 -914, 2006. doi: 10.2215/CJN.00320106 B oth plasma urea and fractional urea excretion (FE urea) are considered as useful biochemical parameters in the differential diagnosis of salt-depleted hyponatremic and patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) (1-3). Hyponatremia in SIADH is usually associated with a low plasma urea as a result of a high FE urea (4), whereas in hyponatremia that is caused by salt depletion (SD), plasma urea usually is increased as a result of an abnormal low FE urea (5) (prerenal uremia). Unfortunately, the usefulness of plasma urea and FE urea in discriminating SIADH and SD is limited by an important degree of "overlapping" values. In earlier work (6), we noted that plasma urea values Ͼ30 mg/dl were observed in 82% of patients with SD, whereas plasma urea values Ͻ30 mg/dl were seen in 79% of patients with SIADH. Eighty-two percent of the patients with salt-depleted hyponatremic presented FE urea values Ͻ50%, but only 52% of the patients with SIADH showed FE urea values Ͼ50...

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“…Significant changes failed to materialize in the older group for successive comparisons of AVP levels, whereas the young subjects had a much lower baseline level, demonstrated a marked increase during the infusion, and a precipitate decline subsequent to drinking. The age-related attenuation of AVP responses to hypertonic infusion and drinking has precedent in other experimental manipulations of thirst (29). There is evidence from human and animal experimentation to suggest that afferent input from the oropharangeal region is particularly important for the inhibition of AVP release subsequent to drinking (30,31).…”

Section: Discussionmentioning

confidence: 99%

Effect of aging on regional cerebral blood flow responses associated with osmotic thirst and its satiation by water drinking: A PET study

Farrell

Zamarripa

Shade

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Levels of thirst and ad libitum drinking decrease with advancing age, making older people vulnerable to dehydration. This study investigated age-related changes in brain responses to thirst and drinking in healthy men. Thirst was induced with hypertonic infusions (3.1 ml/kg 0.51M NaCl) in young (Y) and older (O) subjects. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET). Thirst activations were identified by correlating rCBF with thirst ratings. Average rCBF was measured from regions of interest (ROI) corresponding to activation clusters in each group. The effects of drinking were examined by correlating volume of water drunk with changes in ROI rCBF from maximum thirst to postdrinking. There were increases in blood osmolality (Y, 2.8 ؎ 1.8%; O, 2.2 ؎ 1.4%) and thirst ratings (Y, 3.1 ؎ 2.1; O, 3.7 ؎ 2.8) from baseline to the end of the hypertonic infusion. Older subjects drank less water (1.9 ؎ 1.6 ml/kg) than younger subjects (3.9 ؎ 1.9 ml/kg). Thirst-related activation was evident in S1/M1, prefrontal cortex, anterior midcingulate cortex (aMCC), premotor cortex, and superior temporal gyrus in both groups. Postdrinking changes of rCBF in the aMCC correlated with drinking volumes in both groups. There was a greater reduction in aMCC rCBF relative to water drunk in the older group. Aging is associated with changes in satiation that militate against adequate hydration in response to hyperosmolarity, although it is unclear whether these alterations are due to changes in primary afferent inflow or higher cortical functioning.cingulate cortex ͉ positron emission tomography U nder usual ambient conditions, volumes of water sufficient to maintain fluid balance are consumed in the routine of regular meals (1, 2). Heat or vigorous activity may cause dehydration, resulting in thirst and the desire to drink. Aging alters thirst and drinking responses, making older people vulnerable to body fluid imbalance (3). This study compared the pattern of brain responses in younger and older men during the development and the satiation of thirst. The aim of the study was to assess the role of cortical and subcortical processes in agerelated changes of thirst and drinking.There are two major physiological changes that cause the onset of thirst; increased blood/CSF osmolality and decreased volume of extracellular fluid. Studies differ on the effects of aging on the relations among blood tonicity, blood volume, and thirst. Increase of blood osmolality through the systemic infusion of hypertonic solutions has been reported to demonstrate either no age-related change in thirst ratings (4, 5) or decreased thirst responses in older men (6). Head-out water immersion drives water into the intrathoracic cavity, leads to increased blood volume and cardiac filling pressure in both young and older subjects, and has been used to assess the effects of blood volume changes on thirst ratings. Head-out immersion leads to a decrease in thirst in young subjects, but does not change thirst ratings in older subjects...

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Effects of drinking on thirst and vasopressin in dehydrated elderly men

Cited by 39 publications

References 0 publications

Heat Illness during Working and Preventive Considerations from Body Fluid Homeostasis

Heat Illness during Working and Preventive Considerations from Body Fluid Homeostasis

Age-Related Increase in Plasma Urea Level and Decrease in Fractional Urea Excretion

Effect of aging on regional cerebral blood flow responses associated with osmotic thirst and its satiation by water drinking: A PET study

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