Effects of yohimbine and tolazoline on isoproterenol and angiotensin II-induced water intake in rats.
Subcutaneous administration of the alpha 2-adrenoreceptor antagonists, yohimbine and tolazoline, at doses up to 1000 micrograms/kg, had no effect on water intake of female rats. However, when these compounds were administered SC in combination with either the beta-adrenoreceptor agonist, isoproterenol (10 to 25 micrograms/kg, SC), or with angiotensin II (200 micrograms/kg, SC), water intake was enhanced. In contrast, intraventricular administration of either tolazoline (10 and 20 micrograms/kg) or yohimbine (300 micrograms/kg) failed to augment the dipsogenic response to angiotensin II (150 micrograms/kg, SC). Thus, the enhancing effect of these alpha 2-adrenoreceptor antagonists on isoproterenol- and angiotensin II-induced water intakes appears to be manifested peripherally, rather than centrally. In view of the fact that clonidine, an alpha 2-adrenoreceptor agonist, has been shown to inhibit water intake induced by both isoproterenol and angiotensin II, the results suggest that the alpha 2-adrenoreceptor may play a role in modulating water intake induced by these two dipsogenic agents.
D000804:Angiotensin II / Q000008:administration & dosage*; D000818:Animals; D003000:Clonidine / Q000008:administration & dosage; D004326:Drinking / Q000187:drug effects*; D004347:Drug Interactions; D005260:Female; D007276:Injections, Intraventricular; D007279:Injections, Subcutaneous; D007545:Isoproterenol / Q000008:administration & dosage*; D051381:Rats; D011919:Rats, Inbred Strains; D014043:Tolazoline / Q000008:administration & dosage*; D015016:Yohimbine / Q000008:administration & dosage*
D000804:Angiotensin II; D015016:Yohimbine; D014043:Tolazoline; D007545:Isoproterenol; D003000:Clonidine