Analysis of the water-soluble products of phosphatidylcholine breakdown by ion-exchange chromatography. Bombesin and TPA (12-O-tetradecanoylphorbol 13-acetate) stimulate choline generation in Swiss 3T3 cells by a common mechanism.
A method for the rapid and quantitative separation of glycerophosphocholine, choline phosphate and choline upon ion-exchange columns is described. The method has been utilized to examine the stimulation of phosphatidylcholine breakdown in quiescent Swiss 3T3 cells in response to bombesin and 12-O-tetradecanoylphorbol 13-acetate (TPA). The stimulated generation of choline is shown to precede that of choline phosphate, with no effect upon glycerophosphocholine levels; but was attenuated in cells in which protein kinase C activity was down-regulated. The results thus suggest that stimulation of the cells with either bombesin or TPA activates phospholipase D-catalysed phosphatidylcholine breakdown by a common mechanism involving the activation of protein kinase C.