Studies on the mechanism of action of 3, 4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)-qu inolinone (OPC-8212), a new positive inotropic drug. Enzyme activities and Ca2+ transport processes of sarcolemma and intracellular organelles.

3,4-Dihydro-6-[4-(3,4- dimethoxybenzoyl )-piperazinyl]-2(1H)- quin olinone ( OPC -8212) is a new positive inotropic agent. In studies designed to elucidate information concerning its mechanism of action, its effect on Ca+ transport and related enzyme activities in sarcolemma, sarcoplasmic reticulum and mitochondria were studied. OPC -8212 was found to have little or no effect on these processes. The mechanism of action therefore is clearly different from other known positive inotropic drugs.