Abstract
Summary
The direct effects of d- and dl-propranolol (Inderal) on myocardial adenyl cyclase activity were determined on in vitro preparations from cats and guinea pigs. In both species, dl-propranolol depressed myocardial adenyl cyclase activity at all dose levels greater than 10-8 M. The pure dextroisomer produced less depression of the adenyl cyclase activity. In preparations from reserpinized cats, d-propranolol had no effect on myocardial adenyl cyclase activity up to 10-4 M, while the effects of dl-propranolol were slightly reduced. Since d- and dl-propranolol have identical depressive effects on myocardial contractile force, the present data demonstrate a dissociation between their effects on adenyl cyclase activity and force development.
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