Water metabolism and renal function during hibernation and hypothermia
Deavers, D.R.; Musacchia, X.J.
Federation Proceedings 39(12): 2969-2973
1980
ISSN/ISBN: 0014-9446 PMID: 6998740 Document Number: 168448
Total water turnover in normothermic, 13-lined ground squirrels exposed to cold was about half that predicted from allometric relations of water loss and bodyweight. During hibernation pulmocutaneous water loss and oxygen consumption were 1/77th and 1/52nd of values during normothermia, respectively. Renal function during deep torpor with body temperatures of 8 deg C or lower was also assessed in ground squirrels and hamsters. Results suggest that glomerular filtration and urine formation are absent or undetectable in these animals. The reduction in arterial blood pressure may be the primary adaptation for eliminating filtration. If filtration (which is not thermally vulnerable, being dependent on hydrostatic pressure) occurred, it is difficult to imagine how reabsorption (which has critical metabolic steps such as ion transport that would be thermally vulnerable) could keep pace. Filtration and hypertonic urine formation occur at body temperatures of 20 deg and 30 deg during the arousal process. Marmots differ from other hibernating rodents in that measurable filtration and hypertonic urine formation occur during hibernation.