Concentration of urine by the hibernating marmot [Concentration de l'urine par la marmotte hibernante].

Résumé

L'osmolarité est inférieure de moitié chez les marmottes en hibernation. Studies were performed with marmots (Marmota flaviventris) of both sexes that had chronic arterial, venous, and bladder catheters. Urine collection was performed during hibernation and urine osmolalities (611.6 ± 166.l SD) were found to be lower than those of aroused animals (1264 ± 472.9 SD), but hypertonic to plasma. Peak osmolality of medullary slices was found to be in the range of osmoric pressures of urine obtained from hibernating or aroused animals. After single injections of a mixture of p-aminohippurate and inulin, or during constant infusion of inulin, steady state excretion by hibernators was not achieved for several days. Indirect evidence indicates that the hibernating marmot is capable of PAH secretion.