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DISSOCIATION OF 5‐HYDROXYTRYPTAMINE EFFECTS ON MYOCARDIAL CONTRACTILITY AND CYCLIC AMP ACCUMULATION
Author(s) -
BENFEY B.G.,
COHEN J.,
KUNOS G.,
VERMESKUNOS I.
Publication year - 1974
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.1476-5381.1974.tb08592.x
Subject(s) - contractility , medicine , phenoxybenzamine , inotrope , endocrinology , chemistry , reserpine , adenosine , tyramine , phosphodiesterase inhibitor , biology , propranolol
1 5‐Hydroxytryptamine increased the contractility of the isolated rat atrium and produced a small rise in cyclic 3′,5′‐adenosine monophosphate (cyclic AMP) accumulation in rat heart slices. These effects were similar to those of tyramine. 2 Incubation with phenoxybenzamine prevented the inotropic effect of 5‐hydroxytryptamine but did not inhibit the rise in cyclic AMP accumulation. 3 A single injection of reserpine 24 h before the experiment did not inhibit the inotropic effect of 5‐hydroxytryptamine but prevented the rise in cyclic AMP accumulation. 4 It is concluded that in the rat 5‐hydroxytryptamine increases cardiac contractility chiefly by a direct effect which is blocked by phenoxybenzamine, whereas it increases myocardial cyclic AMP accumulation indirectly by releasing endogenous catecholamines. Cardiac contractility may thus be increased without a rise in cyclic AMP accumulation, and cyclic AMP accumulation may be increased without a rise in contractility.