Effect of 1,25-dihydroxyvitamin D3 on phospholipid composition of rat renal brush border membrane

To analyze the effects of vitamin D on renal tubular cell membrane phospholipid metabolism, the effects of vitamin D depletion and repletion on renal brush border membrane (BBM) phosphatidylethanolamine (PE), phosphatidylcholine (PC), and phosphatidylinositol (PI) were studied. The PC content of BBM from kidneys of rats deprived of vitamin D for 5-6 wk was 33.5 +/- 2.2 nmol Pi/mg protein. This was significantly lower than the PC content of BBM from kidneys of rats supplemented with vitamin D2 for 2 wk, 41.0 +/- 0.4 nmol Pi/mg protein. Vitamin D depletion also decreased the content of BBM PE. The fatty acid composition of BBM PC was altered by vitamin D depletion. Vitamin D depletion increased palmitic acid and decreased stearic, linoleic, and arachidonic acid. Vitamin D repletion with a single physiological dose of 1,25(OH)2D3 (30 pmol), 16 h prior to study tended to increase membrane content of PC and significantly increased the linoleic acid content of the PC fraction. Single-dose vitamin D repletion with a pharmacological dose of 1,25(OH)2D3 (2.4 nmol) produced a significant increase in BBM content of PC and also significantly increased the linoleic acid content of PC. These results demonstrate that vitamin D deficiency affects PC and PE content of rat renal BBM and their fatty acid composition, and that vitamin D repletion with 1,25(OH)2D3 for 16 h partially normalizes the changes in PC.