Effects of d,l-Propranolol, d-Propranolol, l-Propranolol, and Sotalol on Myocardial Contractility and Coronary Resistance
- 1 February 1973
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Physiology and Pharmacology
- Vol. 51 (2) , 61-67
- https://doi.org/10.1139/y73-009
Abstract
The effects of d,l-propranolol, d-propranolol, l-propranolol, and sotalol on myocardial contractility and vascular coronary resistance (V.C.R.) were studied on isolated perfused rat and guinea pig hearts, using a modified Langendorff technique. Left ventricular intracavitary pressure (L.V.P.) and maximum dp/dt were depressed by d,l-propranolol and d-propranolol but not by sotalol and l-propranolol. At constant coronary flow, perfusion pressure was decreased to 40% of control values by d,l-propranolol and d-propranolol but perfusion pressure remained unchanged with l-propranolol and increased with sotalol. The drop in V.C.R. following d,l-propranolol and d-propranolol preceded the fall of L.V.P. and occurred in fibrillating hearts as well. The same effect was obtained in noradrenaline-depleted hearts following pretreatment with 6-OH-dopamine. These observations suggest that d,l-propranolol has a coronary vasodilator action unrelated to its adrenergic-receptor blocking properties, and which appears specifically to be an effect of its dextro-isomer.Keywords
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