[The functional capacities of the kidneys in hamsters of the genus Phodopus]

Studies have been made on total osmolarity and concentration of Na and K in the urine, as well as on the level of diuresis in three species of the hamsters (Phodopus sungorus, Ph. campbelli, Ph. roborovskii) under the conditions of presence or absence of wet food and during water and salt loading. Mean value of osmotic concentration of the urine at free access to wet food varied within 2,600-3,500 mosmol, under the condition of dry-eating--within, 5,600--6,400 mosmol, which indicates the existence of a highly effective renal mechanism of water economy in the investigated species. At the same time, the capacity to maintain constant body weight in animals fed only air-dried food was noted only in separate specimens. In experiments with water load (30 microliters/g), the volume of fluid excreted within 4 hours amounted up to 87% of the load for Ph. sungorus, 70%--for Ph. campbelli and 43% for Ph. roborovskii. Studies on sodium and potassium contents of the urine under the conditions of dry-eating and salt loading indicate that the species investigated are capable of cation concentrating, yet they do not reveal any special mechanisms accounting for the excretion of excessive salts.