DIPSOGENIC ACTION OF DIAZOXIDE: A PHARMACOLOGIC ANALYSIS

¹ Department of Psychology, Rutgers University, New Brunswick, New Jersey

Diazoxide s.c. produced a pronounced, dose-related, acute, dipsogenic response (intake of 5-6% of the body weight) in water-satiated rats. Further studies showed that this dipsogenic action was not secondary to a diuresis or acute changes in blood volume or ionic concentrations. Dose-related hypotension was observed. Alpha adrenergic blocking with tolazoline increased the dipsogenic response to diazoxide by 38%, while the beta antagonist propranolol decreased the response (by 71% at the largest dose) as a function of dose level. This graded decrease in the dipsogenic response to diazoxide was attributed to an antagonism of its beta adrenergic action by propranolol, although at the largest dose of propranolol employed a smaller decrease in the dipsogenic responses induced by water deprivation (16%) and by NaCl load (35%) was also observed. Muscarinie blockade with atropine produced decrements in water deprivation- and NaCl-induced drinking at te largest dose employed which were as large or larger than the decrease it effected in diazoxide-induced drinking. The muscarinic component, then, is not a specific feature of diazoxide-induced drinking. Adrenalectomy produced no acute change in the dipsogenic response to diazoxide, but nephrectomy eliminated it even in the presence of renin replacement. We conclude that this drinking response has its origin in a renal beta adrenergic response, but that the crucial participation of the renin-angiotensin system has not been demonstrated.