title: Pressor response induced by the hippocampal administration of neostigmine is suppressed by M1 muscarinic antagonist.
abstract: We investigated the roles played by three muscarinic receptors (M1, M2, and M3) in the pressor response with bradycardia that followed the injection of neostigmine (5 x 10(-8) mol) into the hippocampus of anesthetized rats. These changes were blocked by the co-administration of methylatropine (5 x 10(-8) mol). The intrahippocampal injection of pirenzepine (M1 antagonist) (5 x 10(-9) - 5 x 10(-7) mol) suppressed the neostigmine-induced pressor response dose-dependently. However injection of gallamine (M2 antagonist) (5 x 10(-8) - 5 x 10(-7) mol) and of 4-DAMP (M1 and M3 antagonist) (5 x 10(-8) - 5 x 10(-7) mol) did not suppress this hypertensive response. These findings suggest that the neostigmine-induced pressor response with bradycardia is mediated through the M1 muscarinic receptor subtype.
mesh_terms: D000818:Animals; D001286:Atropine Derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D004347:Drug Interactions; D005703:Gallamine Triethiodide / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D009388:Neostigmine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D010277:Parasympathomimetics / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D010890:Pirenzepine / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000145:classification / Q000502:physiology
chemical_list: D001286:Atropine Derivatives; D018727:Muscarinic Antagonists; D010277:Parasympathomimetics; D010880:Piperidines; D011976:Receptors, Muscarinic; D009388:Neostigmine; D010890:Pirenzepine; C006649:methylatropine; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; D005703:Gallamine Triethiodide