The responsiveness of M2-muscarinic receptors in the posterior hypothalamus and brain stem of vasopressin hypertensive rats.
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 M2-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 M2-muscarinic receptors in the brain areas responsible for the regulation of blood pressure.
Szmigielska
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H
Department of Pharmacodynamics, Medical Academy, Lódź, Poland.
Szmigielski
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Szadowska
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D000628:Aminophylline / Q000494:pharmacology; D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D007034:Hypothalamus, Posterior / Q000187:drug effects / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D008236:Lypressin; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism*; D014203:Tremorine / Q000037:antagonists & inhibitors / Q000494:pharmacology
D011976:Receptors, Muscarinic; D000628:Aminophylline; D008236:Lypressin; D014203:Tremorine