Regulation of A1 adenosine receptors by amiodarone and electrical stimulation in rat myocardial cells in vitro

Dalia El-Ani, Kenneth A. Jacobson, Asher Shainberg

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    11 Scopus citations

    Abstract

    The effects of conditions that either increase or decrease heart rate on the pharmacological properties of adenosine receptors in cultured rat myocytes were examined. Levels of A1 adenosine receptors, following prolonged treatment with electrical stimulation (ES) or the antiarrhythmic drug amiodarone, were determined using radioligand binding with the specific A1 receptor antagonist [3H]1,3-dipropyl-8-cyclopentylxanthine (CPX). The effects of lowering temperature were also explored. Exposure to amiodarone for 4 days reduced the density of A1 receptors by 19% (from 24.7 ± 0.4 to 20.09 ± 0.3 fmol/dish) and inhibited the rate of contraction by 60% (from 188 ± 16 to 76 ± 30 beats/min), without changing the receptor affinity, protein content, creatine kinase (CK) activity or cell number. Electrical stimulation at 25°C elevated the density of A1 adenosine receptors by 185% (from 4.1 ± 0.4 to 11.69 ± 2.1 fmol/dish). Four days of reduced temperature (from 37°C to either 30 or 25°C) lowered the density of A, adenosine receptors by 69 or 86%, respectively (from 24.1 ± 1.2 to 7.4 ± 0.4 or 3.4 ± 0.3 fmol/dish), with no significant change in the receptor affinity, activity of CK, or lactate dehydrogenase (LDH), protein content or cell number. The observed up- and down-regular-ion of A1 adenosine receptors in primary myocyte cultures in response to conditions that exogenously alter the rate of contraction, is indicative of the role of adenosine receptors in adaptation of heart cells to stress.

    Original languageEnglish
    Pages (from-to)583-587
    Number of pages5
    JournalBiochemical Pharmacology
    Volume54
    Issue number5
    DOIs
    StatePublished - 1 Sep 1997

    Bibliographical note

    Funding Information:
    We thank A. Isaac and T. Zinmun for their wa!aluabtleec hnical assistance and toA , Goldreich for typing them anuscriptT. his research is supportedby Grant 93-22 from the United States-IsraeBl inational Science Foundation( BSF), Jerusalem,I srael. This work was carried out in partial fulfillment of the requirementfso r a Ph.D. degreefo r D. ELAni.

    Keywords

    • Adenosine receptor
    • Amiodarone
    • Cardiocytes
    • Electrical stimulation
    • Heart rate
    • Temperature

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