FUNCTION, CHARACTERIZATION AND AUTORADIOGRAPHIC LOCALIZATION AND QUANTITATION OF β‐ADRENOCEPTORS IN CARDIAC TISSUES

Peter Molenaar, Fraser D. Russell, Tatsuo Shimada, Roger J. Summers

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Abstract

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.

Original languageEnglish
Pages (from-to)529-533
Number of pages5
JournalClinical and Experimental Pharmacology and Physiology
Volume16
Issue number6
DOIs
Publication statusPublished - 1 Jan 1989

Keywords

  • (—)[ I]‐cyanopindolol
  • (—)‐isoprenaline
  • autoradiography
  • CGP 20712A
  • guinea‐pig heart
  • human right atrial appendage
  • ICI 118,551
  • procaterol
  • receptor binding
  • RO363

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