[Measurement of antidiuretic hormone and plasma renin activity in desert rodents]

Plasma antidiuretic hormone (ADH) and renin activity (PRA) were determined in two species of desert rodent (Jaculus orientalis and Jaculus deserti) under chronic dehydration and were compared to those of Wistar Rat. ADH concentration was very high in the desert animals: 200 times higher than in the Rat on a normal diet and 20 times higher than in the 48 hours-dehydrated Rats. The neurohypophyseal ADH content of these rodents was twice that of the normally hydrates Rat, while the dehydration caused a decrease of neurohypophyseal content in the Rat. Plasma renin activity was respectively 2.6 and 3.7 times higher in Jaculus deserti and Jaculus orientalis than in Rats on normal diet, but it was similar to that of dehydrated Rats. During an experimental chronic dehydration, the renin angiotensin system is moderately activated in the desert rodents; but, there is an intensive stimulation of ADH which may play a primordial role in the maintenance of water balance. Now it is necessary to demonstrate how these mechanisms are involved in the natural environment of the animals.