Effect of intraventricular administration of isoprenaline on urinary function in the goat

Intraventricular infusion of small doses of isoprenaline (ISO) in conscious non-hydrated goats produced a significant diuretic response, as well as a decrease in the excretion rate of Na+, K+ and Cl- in the urine; these effects were dose-dependent. An increase in free water clearance was observed as well. Pretreatment with propranolol, injected into the 3rd ventricle, completely abolished the ISO-induced diuretic effects, whereas phentolamine was ineffective. The data suggest that hypothalamic beta-adrenoreceptors are concerned with an inhibition of vasopressin release, inducing a diuretic response.