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Inhibition by purines of the inotropic action of isoprenaline in rat atria
Author(s) -
Hughes P.R.,
Stone T.W.
Publication year - 1983
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1983.tb11060.x
Subject(s) - adenosine , adenosine receptor , isoprenaline , endocrinology , chemistry , medicine , reserpine , theophylline , adenosine deaminase , adenosine a1 receptor , deoxycoformycin , pharmacology , receptor , biology , biochemistry , agonist , stimulation
1 The effects of a series of adenosine derivatives were examined on the catecholamine‐stimulated electrically‐driven rat left atrium in vitro.2 All the purines tested reduced the positive inotropic action of isoprenaline, 0.1 μ M , with the potency order: L ‐N 6 ‐phenlylisopropyladenosine ( L ‐PIA) > 5′‐N‐ethylcarboxamide adenosine (NECA) > D ‐PIA > 2‐chloroadenosine > adenosine. Dipyridamole did not change the IC 50 of adenosine. The adenosine deaminase inhibitor, 2′deoxycoformycin, produced a small but nonsignificant shift to the left of the adenosine concentration‐response curve. 3 The cardiac depressant effects of these purines were reversed by theophylline and the IC 50 values were unchanged in the presence of atropine or in atria taken from reserpine‐treated rats. 4 It is concluded that the purine receptor mediating these effects should not be classified on the A 1 /A 2 system. The relationship between functionally characterized purine receptors and those originally defined as modulating adenylate cyclase is discussed.