Independent receptors for pressor and drinking responses to central injections of angiotensin II and carbachol.
Angiotensin II and carbachol when injected in the brain ventricles of the rat produce similar responses of an increase in blood pressure and drinking behavior. The question of whether these effects are produced by independent receptors or via a cholinergic circuit is debatable for the drinking behavior and evidence is lacking for the blood pressure effect. We have used a chronic rat preparation for recording blood pressure and drinking at the same time during intraventricular injections (i.v.t.) of both angiotensin and carbachol and i.v.t. or intravenous infusions of appropriate antagonists. The results show that drinking and blood pressure response to angiotensin II can be blocked by P113 (500 ng 1.v.t.) an angiotensin antagonist; they are not blocked by atropine (10 mug i.v.t.) a cholinergic antagonist; carbachol effects, however, are not blocked by P113, but are totally blocked by atropine (10 mug i.v.t.), At high doses of atropine there is inhibition of both agents but this probably represents a general inhibition. The hormone and cholinomimetic administered together interact and both are inhibited by adrenergic stimulation. We conclude from these experiments that angiotensin and carbachol act upon independent receptors in the brain to produce blood pressure and drinking responses but at some point they share common, central effector pathways.
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002217:Carbachol / Q000494:pharmacology*; D002552:Cerebral Ventricles / Q000187:drug effects; D004327:Drinking Behavior / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D051381:Rats; D011930:Reaction Time; D011945:Receptors, Angiotensin / Q000187:drug effects*; D011956:Receptors, Cell Surface / Q000187:drug effects*; D011955:Receptors, Drug / Q000187:drug effects*; D012504:Saralasin / Q000494:pharmacology
D011945:Receptors, Angiotensin; D011956:Receptors, Cell Surface; D011955:Receptors, Drug; D000804:Angiotensin II; D001285:Atropine; D002217:Carbachol; D012504:Saralasin; D010646:Phentolamine