[Effect of fat on renal water excretion under conditions of disorders in the secretion of antidiuretic hormone].

The fat antidiuretic effect was studied in rats with inhereted diabetes insipidus (DI rats). In these animals the decrease of urine flow after fat ingestion was less stable and less profound as compared with non--DI: sunflower oil produced no effect in 12 DI rats out of 19, the per cent of inhibition in the other 7 being not more than 50%. No changes in urine osmalality were observed during the period of fat inhibition, while a significant decrease in creatinine excretion was revealed. Fat antidiuresis in DI rats was not affected by ethanol administration. These findings corroborate the assumption that fat ingestion in healthy animals is accompanied by the ADH release. It seems that changes in glomerular filtration rate are involved in the mechanism of this kind of antidiuretic response, at least in rats with impaired ADH secretion