Caffeine inhibits Ca(2+)-mediated potentiation of inositol 1,4,5-trisphosphate-induced Ca2+ release in permeabilized vascular smooth muscle cells - PubMed (original) (raw)

. 1993 Jul 30;194(2):726-32.

doi: 10.1006/bbrc.1993.1882.

Affiliations

Caffeine inhibits Ca(2+)-mediated potentiation of inositol 1,4,5-trisphosphate-induced Ca2+ release in permeabilized vascular smooth muscle cells

K Hirose et al. Biochem Biophys Res Commun. 1993.

Abstract

We studied the effects of caffeine on inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release in saponin-permeabilized smooth muscle cells. The Ca2+ concentration in the vicinity of the Ca2+ store was strongly buffered to exclude the secondary effect of Ca2+ on the Ca2+ release. 2 mM caffeine shifted the IP3 concentration-Ca2+ release relation at 100 nM Ca2+ to the higher IP3 concentration without decreasing the steepness of the relation. The ascending limb of the biphasic Ca2+ dependence of IP3-induced Ca2+ release was shifted to the higher Ca2+ concentration by 2 mM caffeine. However, caffeine showed little inhibitory effect in the absence of Ca2+. These results indicate that caffeine inhibits IP3-induced Ca2+ release only when the Ca2+ release is potentiated by Ca2+.

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