Mechanism of chlorpropamide antidiuresis

A study was made of the effect of chlorpropamide in rats with pituitary stalk lesion. It was found that the drug made the oliguric interphase more pronounced and protracted, while in the lasting polyuric phase in the absence of endogenous ADH it influenced water intake only moderately. Enhancement of the effect of exogenous ADH was observed after a 2-day chlorpropamide pretreatment. The results support the view that the presence of a small amount of endogenous ADH is necessary for chlorpropamide-antidiuresis. The drug presumably brings about the decrease in diuresis via ADH mobilization, but its peripheral effect is also enhanced.