Urine concentrating ability of arousing and normothermic ground squirrels ( Spermophilus columbianus)

Abstract

1. 1. Determinations of T CH 2O indicate that the urine concentrating ability of ground squirrels ( Spermophilus columbianus) arousing from torpor is similar to that of normothermic squirrels. 2. 2. When squirrels were infused with an osmotic diuretic (1·5% NaCl) the arousing animals demonstrated a maximum T CH 2O whereas no maximum was reached at similar urine flows induced in normothermic squirrels. 3. 3. Urea clearances in infused arousing squirrels were generally much less than those in normothermic squirrels at high urine flows suggesting that restoration of the renal medullary osmotic gradient of arousing animals may be slowed by infusion.