Renal excretion capacity in hydrated desert rodents (Jaculus orientalis and Jaculus deserti)

The capacity to excrete a water load was studied in rats and in two desert rodents (Jaculus orientalis and Jaculus deserti) adapted to either 5 or 30 degrees C ambient temperature. The rat is able to eliminate the entire water load regardless of thermal adaptation. Cold-adapted J. orientalis and J. deserti excreted 60% of the water load in comparison to 20-30% in warm-adapted jerboas. At both adaptation temperatures, antidiuretic hormone (ADH) concentration was estimated at maximum diuresis in the two desert species. Though hydration induced a significant decrease in ADH concentration in both species, its level in the plasma remained relatively high. The decrease was more pronounced in J. orientalis than J. deserti.