PT - JOURNAL ARTICLE AU - C Y Chiou AU - M H Malagodi AU - B V Sastry AU - P Posner TI - Effects of calcium antagonist, 6-(N, N-diethylamino) hexyl-3, 4, 5-trimethoxybenzoate, on digitalis-induced arrhythmias and cardiac contractions. DP - 1976 Aug 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 444--449 VI - 198 IP - 2 4099 - http://jpet.aspetjournals.org/content/198/2/444.short 4100 - http://jpet.aspetjournals.org/content/198/2/444.full SO - J Pharmacol Exp Ther1976 Aug 01; 198 AB - 6-(N, N-Diethylamino) hexyl-3, 4, 5-trimethylbenzoate (TMB-6) and lidocaine were equipotent (1 mg/kg) in the conversion of ectopic rhythms to normal rhythms in digoxin-toxic dogs. However, TMB-6 had fewer side effects on heart rates and dp/dt than lidocaine. TMB-6 inhibited the contractile force of electrically stimulated dog and guinea-pig atria and ventricles at concentrations ranging from 2.5 X 10(-5) to 1.7 X 10(-4) M. Elevation of extracellular Ca++ concentrations from 2.7 to 5.4 mM produced a significant increase in the ID50 of TMB-6 in atria (from 2.5 X 10(-5) to 5.0 X 10(-5) M in dogs and from 7.2 X 10(-5) to 1.0 X 10(-4) M in guinea pigs). TMB-6 (7.3 X 10(-5) to 2.4 X 10(-4) M) depressed the amplitude of Ca++-dependent action potentials in depolarized dog cardiac Purkinje fibers. These results are discussed with regard to the antagonism of TMB-6 on Ca++ availability in the myocardium which leads to the conversion of cardiac arrhythmias.