Biochemical aspects of the mechanism of action of antiarrhythmic drugs on mitochondria. VII. Effect on energy-linked reactions and on membrane potential.

Effects of the antiarrhythmic drugs (propranolol, perhexiline maleate, lidoflazine and iproveratril) on energy-linked reactions and on membrane potential were studied. Propranolol, perhexiline maleate and lidoflazine inhibit the ATPase activity of undamaged and broken mitochondria, and of submitochondrial particles. All drugs are inhibitors of either ATP-driven or of succinate-driven reduction of NADP+. The antiarrhythmics promote a decrease in the membrane potential upon energization of the mitochondrial membrane by alpha-ketoglutarate, succinate, or ATP. It was suggested that these drugs have a primary action on the mitochondrial membrane, thus altering the activities of membrane proteins (channels and enzymes).