Coexistence of beta 1- and beta 2-adrenoceptors in the rabbit heart: quantitative analysis of the regional distribution by (-)-/sup 3/H-dihydroalprenolol binding

Journal Article · Fri Jan 01 04:00:00 EST 1982 · J. Cardiovasc. Pharmacol.; (United States)

DOI:https://doi.org/10.1097/00005344-198201000-00007· OSTI ID:7056335

Brodde, O E; Leifert, F J; Krehl, H J

We determined the amount of beta 1- and beta 2-adrenoceptors in right and left atria and ventricles of rabbits. For this purpose inhibition of specific (-)-/sup 3/H-dihydroalprenolol ((-)-/sup 3/H-DHA) binding (5 nM) by beta 1-selective (practolol, metoprolol) and beta 2-selective (zinterol, IPS 339) adrenergic drugs was determined and analyzed by pseudo-Scatchard (Hofstee) plots. For both atria, inhibition of binding by the four selective beta-adrenergic drugs resulted in non-linear Hofstee plots, suggesting the coexistence of both beta-adrenoceptor subtypes. From these plots we calculated a beta 1:beta 2-adrenoceptor ratio of 72:28 for the right atrium and of 82:18 for the left. In contrast, only a very small amount of beta 2-adrenoceptors (approximately 5-7% of the total beta-adrenoceptor population) could be detected in the ventricles. For comparison we analyzed the inhibition of specific (-)-/sup 3/H-DHA binding in tissues with homogeneous population of beta-adrenoceptors (beta 1:guinea pig left ventricle; beta 2: cerebellum of mature rats). For both tissues the four selective beta-adrenergic drugs showed linear Hofstee plots, demonstrating that in tissues with homogeneous beta-receptor population interaction of each drug with the receptor followed simple mass-action kinetics. We conclude that beta 1- and beta 2-adrenoceptors coexist in rabbit atria while the ventricles are predominantly endowed the beta 1-adrenoceptors.

• Research Organization: Institute of Pharmacology, University of Essen, Federal Republic of Germany
• OSTI ID: 7056335
• Journal Information: J. Cardiovasc. Pharmacol.; (United States), Journal Name: J. Cardiovasc. Pharmacol.; (United States) Vol. 4:1; ISSN JCPCD
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BODY
CARDIOVASCULAR SYSTEM
CHEMISTRY
HEART
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MORPHOLOGY
ORGANS
PHARMACOLOGY
PHYSIOLOGY
RABBITS
REACTION KINETICS
RECEPTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES