HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kardasz, A. M Articles by Hedeskov, C. J Search for Related Content PubMed Articles by Kardasz, A. M Articles by Hedeskov, C. J

Carbamoylcholine regulation of polyphosphoinositide synthesis and hydrolysis in cultured, dispersed, digitonin-permeabilized mouse pancreatic islet cells

Continuing formation of inositol phosphates during stimulation of pancreatic β-cells by hormones and neurotransmitters requires the continued synthesis of the polyphosphoinositides phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5 bisphosphate (PIP₂) from phosphatidylinositol (PI). In the present study we have investigated how this pathway and the activity of phosphoinositide-specific phospholipase C (PI-PLC) are regulated by carbamoylcholine (CCh), Ca²⁺, the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), GTPS and NaF in 44-h [³H]inositol-labelled, dispersed and digitonin-permeabilized mouse pancreatic islet cells.

CCh stimulated not only PI-PLC (G-protein-mediated) but also, by an as yet unknown mechanism, significantly enhanced PI 4-kinase activity, estimated as the PIP:PI ratio, by 100%, and further increased the flux from PI to PIP and PIP₂. GTPS and NaF mimicked the effects of CCh on PI-PLC but had no effect on the levels of PIP and PIP₂. TPA raised the PIP:PI ratio by 75%. In addition TPA counteracted the CCh stimulation of PI-PLC. There was no effect of 10^–6 mol/l Ca²⁺ on the levels of PIP and PIP₂. Experiments with quinacrine and adenosine confirmed that PI-PLC and PI 4-kinase could be regulated independently of each other. In conclusion, these data point to differential regulation of polyphosphoinositide synthesis and breakdown.

European Journal of Endocrinology 136 539–545

This article has been cited by other articles:

				P. Gilon and J.-C. Henquin Mechanisms and Physiological Significance of the Cholinergic Control of Pancreatic {beta}-Cell Function Endocr. Rev., October 1, 2001; 22(5): 565 - 604. [Abstract] [Full Text] [PDF]