title: Positive inotropic action of kappa opiate agonists, ethylketocyclazocine and dynorphin-A(1-13), in isolated rat atrium.
abstract: The effect of various opiate agonists on the contraction of isolated rat atrium was investigated. Ethylketocyclazocine (EKC) (30-100 microM) and dynorphin-A(1-13) (10-30 microM), which are kappa-type agonists, caused positive inotropic effects on electrically stimulated left atrium in a dose-dependent manner. In addition, EKC decreased the frequency of spontaneous beating in the right atrium. Morphine (mu-type), [Met5]- and [Leu5]-enkephalin (delta-type) did not affect both the developed tension and frequency of contractions. These results indicate that the positive inotropic action is specific for kappa-type opiate agonists.
mesh_terms: D000818:Animals; D003496:Cyclazocine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004399:Dynorphins / Q000494:pharmacology*; D004558:Electric Stimulation; D016314:Ethylketocyclazocine; D006321:Heart / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical
chemical_list: D010446:Peptide Fragments; D016314:Ethylketocyclazocine; C026843:dynorphin (1-13); D004399:Dynorphins; D003496:Cyclazocine