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

Biochem Biophys Res Commun. 1993 Jul 30;194(2):726-32. doi: 10.1006/bbrc.1993.1882.

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+.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caffeine / pharmacology*
  • Calcium / metabolism*
  • Calcium / pharmacology*
  • Cell Membrane Permeability
  • Dose-Response Relationship, Drug
  • Drug Interactions
  • Guinea Pigs
  • In Vitro Techniques
  • Inositol 1,4,5-Trisphosphate / pharmacology*
  • Kinetics
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism*
  • Portal Vein / drug effects
  • Portal Vein / metabolism*

Substances

  • Caffeine
  • Inositol 1,4,5-Trisphosphate
  • Calcium