Function, characterization and autoradiographic localization and quantitation of beta-adrenoceptors in cardiac tissues.
1. This paper demonstrates the use of organ bath, radioligand binding and autoradiography to detect beta 1- and beta 2-adrenoceptors in human and guinea-pig cardiac tissues. 2. In organ bath experiments, non-selective and beta 1- and beta 2-adrenoceptor selective agonists produced concentration-dependent inotropic responses in human right atrial appendage. Both subtypes mediate inotropic responses. In guinea-pig right atria chronotropic responses were mediated predominantly through beta 1-adrenoceptors. 3. Receptor binding studies using (-)[125I]-cyanopindolol (CYP) and beta 1- and beta 2-adrenoceptor selective antagonists showed that beta 2-adrenoceptors comprised 25% of the total population of beta-adrenoceptors in guinea-pig right atria. In human right atria the proportion is higher (40%). 4. Quantitative autoradiography was used to determine the location and densities of beta 1- and beta 2-adrenoceptors in guinea-pig heart. Both beta 1- and beta 2-adrenoceptors were distributed on myocardium. The atrioventricular conducting system had a higher density of beta 2-adrenoceptors compared with myocardium.
Molenaar
P
P
Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia.
Russell
F D
FD
Shimada
T
T
Summers
R J
RJ
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001345:Autoradiography; D002396:Catechols; D004983:Ethanolamines / Q000494:pharmacology; D006168:Guinea Pigs; D006321:Heart / Q000033:anatomy & histology; D006801:Humans; D066298:In Vitro Techniques; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010869:Pindolol / Q000031:analogs & derivatives; D017265:Procaterol; D011412:Propanolamines / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D002396:Catechols; D004983:Ethanolamines; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; C018420:Ro 363; D020120:Iodocyanopindolol; D010869:Pindolol; D007545:Isoproterenol; D017265:Procaterol