Abstract
Some of the clinically used muscle relaxants have been reported to exhibit certain effects other than muscular relaxation. Among them the effects upon the cardiovascular system are of clinical importance. This paper dealt with the results of investigating the effects of various muscle relaxants upon ventricular contractile force directly measured by the method of a heart-lever system in dogs. d-Tubocurarine chloride caused a marked decrease in ventricular con-tractile force, associated with a concomitant fall in aortic and pulmonary arterial blood pressure. These changes seemed to be attributed mainly to a direct action of histamine released by d-tubocurarine. Succinylcholine chloride resulted in a transitory increase in ventricular contractile force, associated with a slight rise in aortic blood pressure. These changes seemed, to be due to a sympa-thomimetie action of succ.inylcholine. Decamethonium bromide, hexamethylene-1, 6-bis-carbaminoylcholine iodide, gallamine triethiodide as well as diallyl-nor-toxiferine showed little effects upon ventricular contractile force.
