Experiments were carried out to assess the effects of secretagogues on the polyphosphoinositides phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] on preparations of exocrine pancreas in vitro. Carbachol and caerulein provoked a rapid (less than 1 min) breakdown of 15-20% of [32P]PtdIns(4,5)P2 in isolated pancreatic acini, but did not affect [32P]PtdIns4P. In contrast, the Ca2+ ionophore ionomycin had no immediate effect on the levels of either inositide but caused a parallel fall in both lipids after 5-10 min. A similar decrease in [32P]PtdIns(4,5)P2 due to carbachol was obtained with isolated acini and isolated cells, despite the fact that the secretory response of isolated cells was considerably less than that of isolated acini. Loss of [32P]PtdIns(4,5)P2 elicited by carbachol or caerulein was unaffected either by the addition of EGTA in excess of extracellular Ca2+ or when a protocol was employed that eliminated caerulein-induced intracellular Ca2+-release. These results suggest that agonist-induced PtdIns(4,5)P2 breakdown in the exocrine pancreas may be an early step in the stimulus-response coupling pathway and also suggest that this breakdown is not dependent on Ca2+-mobilization.
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May 1983
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Research Article|
May 15 1983
Effects of secretagogues on [32P]phosphatidylinositol 4,5-bisphosphate metabolism in the exocrine pancreas Available to Purchase
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1983 London: The Biochemical Society
1983
Biochem J (1983) 212 (2): 483–488.
Citation
J W Putney, G M Burgess, S P Halenda, J S McKinney, R P Rubin; Effects of secretagogues on [32P]phosphatidylinositol 4,5-bisphosphate metabolism in the exocrine pancreas. Biochem J 15 May 1983; 212 (2): 483–488. doi: https://doi.org/10.1042/bj2120483
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