The responsiveness of M2-muscarinic receptors in the posterior hypothalamus and brain stem of vasopressin hypertensive rats
Szmigielska, H.; Szmigielski, A.; Szadowska, A.
Polish Journal of Pharmacology 45(3): 291-298
1993
ISSN/ISBN: 1230-6002 PMID: 8220662 Document Number: 411338
The response of an endogenous inhibitor of cAMP-dependent protein kinase (type I inhibitor) to tremorine was used as an index of sensitivity of control muscarinic M-2-receptors. Tremorine induced a dose-dependent increase in Type I inhibitor activity in the posterior hypothalamus and brain stem. The action of the compound was blocked by pretreatment with aminophylline and atropine. Prolonged, 28 days treatment with lysine vasopressin (1 U/kg/day ip) induced hypertension and modified the dose-response curve for tremorine. Five times higher doses of tremorine than in normotensive rats were necessary to induce statistically significant increase in type I inhibitor activity in the posterior hypothalamus and brain stem suggesting subsensitivity of M-2-muscarinic receptors in the brain areas responsible for the regulation of blood pressure.