Uptake of 32P-orthophosphate and incorporation into phospholipids in Tetrahymena pyriformis W exposed to phenothiazine derivatives

Abstract

Partial inhibition of growth of Tetrahymena pyriformis W by promazine or chlorpromazine resulted in a 60% increase in phospholipid concentration during the exponential phase. Age or drug treatment did not affect the pattern of phospholipids as shown by thin-layer chromatography. At least 8 phospholipid components were recognized, of which phosphatidylethanolamine accounted for almost 50% of the total lipid phosphorus and phosphatidylcholine for about 20%. Uptake of 32P-orthophosphate by resting cells from cultures in the exponential phase was inhibited by chlorpromazine, promazine, promethazine, trifluoperazine, prochlorperazine, acetophenazine, and 2,4-dinitrophenol.Chlorpromazine and 2,4-dinitrophenol differed from one another in their effect on the distribution of 32P-orthophosphate among the principal phosphorus compounds of the cell; in the pattern of labelling of phospholipids with 32P, as shown by autoradiography of thin-layer chromatograms; and in the magnitude of specific activity values for individual phospholipids. These findings showed that the mechanism(s) by which phenothiazine derivatives alter the distribution of absorbed 32P and its incorporation into phospholipids in Tetrahymena differs from that of 2,4-dinitrophenol and that this may be associated with the ability of the tranquilizing drugs to inhibit nutrient uptake by the cells.