title: Blockade of brain M2 muscarinic receptors lowers blood pressure in spontaneously hypertensive rats.
abstract: Injections of the M2 muscarinic receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; 1.5-40 micrograms) into the cerebral ventricles of urethane-anesthetized rats caused a dose-related inhibition of the pressor response to intravenously injected physostigmine. A similar reduction was obtained with 1/80th the dose of methylatropine, but not with the selective M1 antagonist pirenzepine. Intraventricular injection of 4-DAMP (6.25-25 micrograms) caused a dose-related reduction in blood pressure in unanesthetized spontaneously hypertensive rats (SHR), but not in normotensive controls. Systolic pressure fell 42 +/- 6 mm Hg at the 25-micrograms dose. Pirenzepine did not lower blood pressure in SHR and inhibited the antihypertensive effect of 4-DAMP.
authors.affiliation: Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Newark.
authors.forename: H E
authors.initials: HE
authors.lastname: Brezenoff
authors.forename: H
authors.initials: H
authors.lastname: Vargas
authors.forename: Y F
authors.initials: YF
authors.lastname: Xiao
mesh_terms: D000818:Animals; D001286:Atropine Derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D008297:Male; D010276:Parasympatholytics / Q000494:pharmacology*; D010277:Parasympathomimetics / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D011921:Rats, Inbred WKY
chemical_list: D001286:Atropine Derivatives; D010276:Parasympatholytics; D010277:Parasympathomimetics; D010880:Piperidines; C006649:methylatropine; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; D010830:Physostigmine