Effect of thirsting on the biological half-life and organ-distribution of 3H-lysin vasopressin.

The biological half-life and organ-distribution of radiochemically pure, biologically active 3H-lysin vasopressin were determined in normally hydrated and in thirsting rats. Three-day thirsting did not vary the biological half-life of the 3H-LVP. The highest 3H-LVP uptake was observed in the neurohypophysis and adenohypophysis of the normally hydrated rats. As a result of thirsting, the accumulation of labelled vasopressin was increased in the neurohypophysis. The results permit the conclusion that the uptake of vasopressin by the neurohypophysis of rat is enhanced at the time of exocytosis and microvesicle formation induced by dehydration.