On a dual role for clonidine stimulation of the ventromedial nucleus of the hypothalamus in sodium and potassium renal excretions of rats.

The effects of clonidine on sodium and potassium excretions were examined after previous administration of prazosin (an alpha 1-adrenergic receptor antagonist) and yohimbine (an alpha 2-adrenergic receptor antagonist) into the ventromedial nucleus of the hypothalamus of conscious rats. Clonidine injected into the ventromedial nucleus of the hypothalamus induced inhibitory and facilitatory effects on the urinary sodium and potassium excretions. The results suggest that facilitatory effects of clonidine on natriuresis and kaliuresis are mediated through activation of alpha 1-adrenoceptors and that inhibitory effects require alpha 2A-adrenoceptors.