Changes in kidney response to ADH under hypogravity: rat models and possible mechanisms.

Brattleboro homo- (DI) and heterozygous (HZ) rats with total or partial deficiency of the antidiuretic hormone (ADH) and also 10-14-day old Wistar rats irresponsive to ADH were used to examine the possible causes of inadequate responses to ADH in cosmonauts after space flights and in humans after prolonged bedrest in antiorthostasis (-60). The experimental results suggested that changes in the intrarenal osmotic gradients, as well as in the aggregate state of the ADH receptors as a result of the decreased ADH blood level under hypogravitation, might be a cause of the inadequate response to ADH in cosmonauts during readaptation to the Earth's gravity.