Abstract
Phosphatidylinositol (PtdIns), phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-diphosphate [PtdIns(4,5)P2] were isolated from the pancreas of rats fed an ethanol-containing liquid diet for 24 days and from the corresponding pair-fed controls. The isolation involved chromatography on a lipophilic anion exchanger in the phosphate form. The species composition was determined by fast-atom bombardment mass spectrometry. The compositions of PtdIns4P and PtdIns(4,5)P2 were similar to that of PtdIns, with the stearoyl/arachidonoyl species constituting about 32% of the total, compared with 38% in PtdIns. PtdIns(4,5)P2 contained a larger fraction of fully saturated species than PtdIns. The PtdIns species having an arachidonoyl group were about half as abundant in the ethanol-treated as in the control rats. The differences between ethanol-fed and control rats were qualitatively similar for PtdIns, PtdIns4P and PtdIns(4,5)P2, but were less marked for PtdIns4P and PtdIns(4,5)P2. The results indicate that the species compositions of PtdIns4P and PtdIns(4,5)P2 reflect that of PtdIns, and that the changes of PtdIns4P and PtdIns(4,5)P2 in ethanol-treated rats are secondary to changes in PtdIns.