PHOSPHOLIPASE-C AND PHOSPHOLIPASE-D ARE INDEPENDENTLY ACTIVATED IN RAT HIPPOCAMPAL SLICES

In order to investigate a possible G-protein-mediated activation of ph ospholipase D (PLD) and its relationship to the activation of phosphoi nositide-specific phospholipase C (PI-PLC), we measured the effects of aluminium fluoride and carbachol on choline release, the PLD-specific transphosphatidylation reaction (generation of phosphatidylpropanol) and the formation of inositol phosphates in rat hippocampal slices. Al uminium fluoride markedly enhanced the formation of choline and phosph atidylpropanol but failed to increase the formation of inositol phosph ates. In contrast, the muscarinic agonist carbachol strongly stimulate d PI-PLC but failed to activate PLD. We conclude that PLD in hippocamp al slices is activated by a G-protein independently of phosphoinositid e hydrolysis.