The effect of thiamylal and propanidid on the isolated heart muscle in comparison with CT 1341.

IWATSUKI, N. The Effect of Thiamylal and Propanidid on the Isolated Heart Muscle in Comparison with CT 1341. Tohoku J. exp. Med ., 1973, 110 (1), 3340 Inotropic effects of thiamylal and propanidid on the contractile state of the isolated dog heart muscle were determined by means of force-velocity relations and compared with those of CT 1341, a new steroid anesthetic. All anesthetics studied produced a dose-dependent leftward shift of the force-velocity curves, indicating a negative inotropism. The percentage decreases in the maxi mum velocity of muscle shortening (Vmax) and isometric peak force (F) at the concentrations for the clinical induction doses were 5.1•}2.8 and 13.2•}4.3 for thiamylal, 30.9•}4.6 and 61.4•}6.3 for propanidid, and 5.8•}2.4 and 20.2•}2.0 for CT 1341. The changes in Vmax and F were not statistically significant between thiamylal and CT 1341, but clearly significant between propanidid and other two agents. These findings indicate that the depressive effects of thiamyl al and CT 1341 on the myocardium seem to be minor and of a similar degree when they are used at the clinical induction doses, while propanidid may produce a definite negative inotropic effect even at the clinical induction dose. isolated heart muscle; force-velocity relation; inotropism; thiamylal; propanidid; CT 1341