title: Different Myocardial Sensitivity in Newborn and Mature Rats to Selective Stimulation of M3 Cholinoreceptors.
abstract: The effects of selective activation of subtype 3 muscarinic (M3) receptors on electrical activity of isolated preparations of the atrial and ventricular myocardium of the newborn and 4-month-old rats were examined. Application of muscarinic receptor agonist pilocarpine (10(-5) M) in preparations with M2 cholinoreceptors blocked by selective antagonist methoctramine (10(-7) M) decreased the duration of action potentials in the atrial and ventricular myocardium. Selective blocker of M3 cholinoreceptors 4-DAMP (10(-8) M) prevented this effect. While stimulation of ventricular M3 cholinoreceptors with pilocarpine was significantly stronger in newborn pups than in mature rats, similar stimulation of atrial receptors revealed no significant difference in both groups.
authors.affiliation: Department of Human and Animal Physiology, M. V. Lomonosov Moscow State University, Moscow, Russia.
authors.forename: S V
authors.initials: SV
authors.lastname: Tapilina
authors.forename: D V
authors.initials: DV
authors.lastname: Abramochkin
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D003959:Diamines / Q000494:pharmacology; D006325:Heart Atria / Q000187:drug effects* / Q000254:growth & development; D006352:Heart Ventricles / Q000187:drug effects* / Q000254:growth & development; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010862:Pilocarpine / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D043585:Receptor, Muscarinic M2 / Q000037:antagonists & inhibitors; D043587:Receptor, Muscarinic M3 / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D003959:Diamines; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D010880:Piperidines; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D010862:Pilocarpine; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; C054938:methoctramine