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FUNCTION, CHARACTERIZATION AND AUTORADIOGRAPHIC LOCALIZATION AND QUANTITATION OF β‐ADRENOCEPTORS IN CARDIAC TISSUES
Author(s) -
Molenaar Peter,
Russell Fraser D.,
Shimada Tatsuo,
Summers Roger J.
Publication year - 1989
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1989.tb01600.x
Subject(s) - function (biology) , chemistry , characterization (materials science) , adrenergic receptor , medicine , biology , receptor , microbiology and biotechnology , biochemistry , materials science , nanotechnology
SUMMARY 1. This paper demonstrates the use of organ bath, radioligand binding and autoradiography to detect β 1 ‐ and β 2 ‐adrenoceptors in human and guinea‐pig cardiac tissues. 2. In organ bath experiments, non‐selective and β 1 ‐ and β 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 β 1 ‐adrenoceptors. 3. Receptor binding studies using (—)[ 125 I]‐cyanopindolol (CYP) and β 1 ‐ and β 2 ‐adrenoceptor selective antagonists showed that β 2 ‐adrenoceptors comprised 25% of the total population of β‐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 β 1 ‐ and β 2 ‐adrenoceptors in guinea‐pig heart. Both β 2 ‐ and β 2 ‐adrenoceptors were distributed on myocardium. The atrioventricular conducting system had a higher density of β 2 ‐adrenoceptors compared with myocardium.