Colecystokinin octapeptide CCK-8 and carbachol reduce [P-32]orthophosphatelabeling of phosphatidylcholine without modifying phospholipase D activityin rat pancreatic acini

We have studied phospholipase D activation in [P-32]orthophosphoric acid-pr elabeled rat pancreatic acini by measuring the formation of P-32-phosphatid ylalcohols as stimulated in the presence of ethanol or butanol, A small but significant and time-dependent basal accumulation of [P-32]phosphatidyleth anol and [P-32]phosphatidylbutanol was detected, which was further stimulat ed by phorbol myristate acetate, orthovanadate and pervanadate. However, th e secretagogues cholecystokinin octapeptide and carbachol did not enhance b asal accumulation of P-32-phosphatidylalcohol, yet they decreased [P-32]pho sphatidylcholine content and stimulated the generation of [P-32]phosphatidi c acid. Our results stress the need to examine the transphosphatidylation r eaction as well as agonist effects on the synthesis of phosphatidylcholine in order to assess unambiguously phospholipase D activity. (C) 2000 Federat ion of European Biochemical Societies. Published by Elsevier Science B,V, A ll rights reserved.