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Exp Clin Endocrinol Diabetes 1995; 103(5): 280-284
DOI: 10.1055/s-0029-1211364
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© J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York

Calmodulin antagonist W7 increases inositol phosphates in insulin secreting RINm5F cells

A. Waheed1 , I. Koopmann2 , H. P. T. Ammon2
  • 1Dept. of Biochemistry, Ayub Medical College, Abbottabad, Pakistan
  • 2Department of Pharmacology, Institute of Pharmaceutical Sciences, University of Tübingen, Germany
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Publication History

Publication Date:
15 July 2009 (online)

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Summary

W7, a calmodulin antagonist, has been reported to increase cytosolic free calcium concentration [Ca2+]i in non stimulated rat insulinoma cells (RINm5F). And this effect was not due to enhanced calcium uptake. In the present study the effect of calmodulin antagonist W7 on the inositol phosphate turnover of RINm5F cells was studied. Inositol phosphates were separated using a new modified technique of anion-exchange high performance liquid chromatography (HPLC). It was observed that W7 significantly increased inositol trisphosphate and inositol bis-phosphate within 5 and 15 sec, respectively. No changes of inositol phosphates were detected employing W5, a chlorine-deficient analogue of W7 without calmodulin antagonistic action. Our data are in favour of the view that (I) calmodulin may be involved in inositol phosphate metabolism of RINm5F cells and that (II) the increase of [Ca2+]i in response to W7 as reported previously may be due to elevation of inositol trisphosphate.

Key words

Inositol phosphates - RINm5F cells - calmodulin antagonist