Neural lobe function in aged Wistar/Tw strain rats showing polydipsia and polyuria.

Kobayashi, Yuta; Lederis, K.; Kawashima, Seiichiro

doi:10.1507/endocrj1954.33.617

Cited by 4 publications

(4 citation statements)

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“…However, UV was also greater in old rats, both as absolute and body weight-adjusted measures, and the urine from old rats was more dilute. This is consistent with the reduced concentrating ability of the aged kidney that has been observed by others (4,16,21,23).…”

Section: Discussionsupporting

confidence: 92%

“…Differences in ad libitum intakes between young and old rats seem to depend on strain and whether intakes are adjusted for body weight. There are reports of increased daily water intakes in old Wistar (16) , F344 (4, 30, 34), and SD rats (14,22,30) compared with the young animals of these strains. Others report equivalent daily water intakes between young and old Lewis (35) or Wistar rats (36) and decreased daily water intakes in old F344 ϫ BN rats (33).…”

Section: Discussionmentioning

confidence: 99%

“…As in elderly humans, kidneys of aging rats have diminished capacity to concentrate urine (4,16,21,23) and to release renin when challenged (1-3, 28). However, there are only a few studies in aging rats investigating the capacities of behavioral systems, namely, thirst and salt appetite, to supply sufficient water and sodium to maintain adequate hydration.…”

mentioning

confidence: 99%

“…However, there are only a few studies in aging rats investigating the capacities of behavioral systems, namely, thirst and salt appetite, to supply sufficient water and sodium to maintain adequate hydration. Investigators variously report that old rats have diminished (14,23,33), increased (4,14,16,22), or unchanged (35,36) daily intakes of water compared with young cohorts. Compared with young rats, old rats reportedly drink equivalent (30) or smaller (33) amounts of water in response to water deprivation and exogenously administered ANG II.…”

mentioning

confidence: 99%

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Thirst and salt appetite responses in young and old Brown Norway rats

Thunhorst

Johnson²

2003

American Journal of Physiology-Regulatory, Integrative and Comp

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Thunhorst, Robert L., and Alan Kim Johnson. Thirst and salt appetite responses in young and old Brown Norway rats. Am J Physiol Regul Integr Comp Physiol 284: R317-R327, 2003. First published October 10, 2002 10.1152/ ajpregu.00368.2002 Norway rats aged 4 mo (young) and 20 mo (old) received a series of experimental challenges to body fluid homeostasis over ϳ3 mo. Water was available for drinking in some tests, and both water and 0.3 M NaCl were available in others. The series included three episodes of extracellular fluid depletion (i.e., furosemide ϩ 20 h of sodium restriction), two tests involving intracellular fluid depletion (i.e., hypertonic saline: 1 or 2 M NaCl at 2 ml/kg body wt sc), one test involving overnight food and fluid restriction, and testing with captopril adulteration of the drinking water (0.1 mg/ml) for several days. Old rats were significantly heavier than young rats throughout testing. Old rats drank less water and 0.3 M NaCl after sodium deprivation than young rats, in terms of absolute and body weightadjusted intakes. Old rats drank only half as much water as young rats in response to subcutaneous hypertonic NaCl when intakes were adjusted for body weight. Old rats drank less 0.3 M NaCl than young rats after overnight food and fluid restriction when intakes were adjusted for body weight. In response to captopril adulteration of the drinking water, young rats significantly increased daily ingestion of 0.3 M NaCl when it was available as an alternative to water and significantly increased daily water intakes when only water was available, in terms of absolute and body weight-adjusted intakes. Old rats had no response to captopril treatment. These results add important new information to previous reports that aging rats have diminished thirst and nearabsent salt appetite responses to regulatory challenges. aging; drinking; diuresis; natriuresis; dehydration; hypovolemia ELDERLY HUMANS CONSUME ADEQUATE fluids on a daily basis (7). Yet dehydration is a major health risk for the elderly (5), and the elderly are susceptible to dehydration because of increased fluid losses (41). Aged kidneys have a decreased ability to concentrate urine (17, 27) and to conserve sodium (8), along with a relative resistance to vasopressin (25), and release less renin when challenged (6). These changes with age predispose the elderly to hypovolemia and dehydration because of the reduced ability to conserve water and sodium during times of relative water and sodium loss. The elderly have decreased thirst sensation (24, 26, 32). As a result, they are slower than young people to restore fluid balance after exercise-induced dehydration (19) and water deprivation (26). It thus appears that the elderly are more vulnerable to the consequences of physiological challenges to body fluid homeostasis and that diminished thirst in the elderly contributes to their problems of fluid balance (15).The capacities of the aging kidney have been extensively investigated in rat models of aging. As in elderly humans, kidneys of aging r...

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Section: Discussionsupporting

confidence: 92%