Role of phosphatidylserine in the cellular and subcellular lung distribution of quinidine in rats.

The role of phosphatidylserine in the cellular and subcellular lung distribution of quinidine was investigated in rats, since quinidine was found to bind preferentially to phosphatidylserine. The concentration of phosphatidylserine in the cellular and subcellular fractions was determined after separation by two-dimensional thin-layer chromatography. Selective accumulation of quinidine in vivo was observed in the alveolar macrophage at the cellular level and in the plasma membrane at the subcellular level. Both alveolar macrophages and plasma membranes were rich in phosphatidylserine compared to other fractions. When plasma levels were kept at steady state by i.v. infusion, the distribution of quinidine in the lung cellular and subcellular fractions was linearly correlated with the concentration of phosphatidylserine (r = 0.906). These results suggest that the concentration of phosphatidylserine is a dominant determinant of the cellular and subcellular lung distribution of quinidine.