Effect of phospholipid acyl chain modulation on vitamin E incorporation into pulmonary artery endothelial cell...

Incorporation of vitamin E (alpha-tocopherol) was measured in total membranes of pulmonary artery endothelial cells (PAEC) following treatment with eight synthetic phosphatidylethanolamines (PE) (Palmitoyloleoyl, 16:0-18:1 PE1; distearoyl, 18:0-18:0 PE2; dioleoyl, 18:1-18:1 PE3; stearoyl- linoleoyl, 18:0-18:2 PE4; dilinoleoyl, 18:2-18:2 PE5; stearoyl-arachidonyl, 18:0-20:4 PE6; diarachidonyl, 20:4-20:4 PE7; and stearoyl-docosahexenoyl, 18:0-22:6 PE8). Endogenous PE content of native membranes was 0.88 +/- 0.01 nmol/mg protein. Incorporation of PE irrespective of fatty acid content significantly (P < 0.02) increased the PE content of total membranes. Vitamin E incorporation in control membranes was 63 +/- 9 nmol/mg protein. Incorporation of vitamin E in PE1- to PE7-treated cells were significantly (P < 0.05) increased compared to controls and were comparable to each other. Vitamin E incorporation into PE8-treated cells was threefold greater (P < 0.001) than controls and twofold greater (P < 0.001) than PE1- to PE7-treated cells. Increased PE content results in increased vitamin E incorporation into PAEC membranes irrespective of the fatty acids present on the acyl chain, and maximal incorporation of vitamin E in PE8-treated cells may relate to the increased carbon chain length rather than to the degree of unsaturation at the sn2 position.