title: Role of ganglionic M-1 and M-2 receptors in the neuronal control of the cardiovascular system of the normotensive rat as determined with pilocarpine.
abstract: The adrenoceptors involved in the increase in diastolic pressure and heart rate elicited by i.v. administration of pilocarpine to the pithed rat were assessed using as pharmacological tools the alpha 1-adrenoceptor antagonist prazosin, the alpha 2-adrenoceptor antagonist rauwolscine, the beta 1-adrenoceptor blocker atenolol and the beta 2-adrenoceptor blocker ICI 118,551. Pilocarpine indirectly activated vascular alpha 1- and cardiac beta 1-adrenoceptors. By using the M-1 antagonist pirenzepine and the mixed M-1/M-2 antagonist dexetimide, pilocarpine was shown to be a mixed M-1/M-2 agonist. Pilocarpine initiated antagonistic effects on intrasynaptic alpha 2-adrenoceptor-mediated pressor responses and not on those triggered by extrasynaptic alpha 2-adrenoceptors. During vasopressin infusion to counteract a possible vasodilator action of pilocarpine, it was demonstrated that pilocarpine indirectly activated alpha 1- and alpha 2-adrenoceptors. The results support the hypothesis that intra- and extrasynaptic alpha 2-adrenoceptors comprise different populations and that the neuronal control of alpha 2-adrenoceptors is mediated by ganglionic M-2 receptors.
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects / Q000294:innervation*; D003971:Diastole; D005724:Ganglia / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D010862:Pilocarpine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D014667:Vasopressins / Q000494:pharmacology
chemical_list: D011942:Receptors, Adrenergic, alpha; D011976:Receptors, Muscarinic; D010862:Pilocarpine; D014667:Vasopressins