Phosphatidylinositol Turnover in Madin-Darby Canine Kidney Cells: Comparison of Stimulation by A23187 and 12-O-Tetradecanoyl-Phorbol-13-Acetate

Summary

Treatment of Madin-Darby canine kidney cells (MDCK) with either A23187 or 12-O-tetradecanoyl-phorbol13-acetate (TPA) causes a rapid deacylation of [³H]arachidonic acid from membrane phospholipids and an increased production of [³H]prostaglandins (Daniel et al., 1984). The present study revealed that A23187 in contrast to TPA stimulated a rapid increase in the incorporation of “P. P. or [³H] myo-inositol into phosphatidylinositol (PI). However, TPA did increase the incorporation of ³²P_i. into phosphatidylcholine. Neither A23187 nor TPA stimulated the incorporation of ³²P_i. into phosphatidylinositol 4-phosphate (PIP) or phospIatidyl inositol 4, 5-bisphosphate (PIP₂). Present and previous data indicate that phosphatidylinositol turnover is not a required event for the stimulation of arachidonic acid release and prostaglandin synthesis in TPA stimulated MDCK cells.