The influence of amobarbital and ouabain on calcium binding to phospholipids isolated from cardiac sarcoplasmic reticulum.

Abstract Calcium binding to phospholipid, prepared from isolated canine myocardial sareoplasmic reticulum, was facilitated by amobarbital and unaltered by ouabain. Ouabain, however, did antagonize the amobarbital facilitation of calcium uptake. These results indicate that amobarbital reacts chemically with phospholipids and that ouabain antagonizes this reaction. The negative inotropic action of barbiturates may thus be explained by their interaction with phospholipids, perhaps those of the sarcoplasmic reticulum. The ouabain reversal of barbiturate depression of the myocardium could, in part, be explained by its ability to antagonize this barbiturate-phospholipid interaction.