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Calcium-induced calcium release (CICR) may function widely in calcium-mediated cell signaling, but has been most thoroughly characterized in muscle cells. In a homogenate of sea urchin eggs, which display transients in the intracellular free calcium concentration ([Ca2+]i) during fertilization and anaphase, addition of Ca2+ triggered CICR. Ca2+ release was also induced by the CICR modulators ryanodine and caffeine. Responses to both Ca2+ and CICR modulators (but not Ca2+ release mediated by inositol 1,4,5-trisphosphate) were inhibited by procaine and ruthenium red, inhibitors of CICR. Intact eggs also displayed transients of [Ca2+]i when microinjected with ryanodine. Cyclic ADP-ribose, a metabolite with potent Ca(2+)-releasing properties, appears to act by way of the CICR mechanism and may thus be an endogenous modulator of CICR. A CICR mechanism is present in these nonmuscle cells as is assumed in various models of intracellular Ca2+ wave propagation.

Original publication




Journal article


Science (New York, N.Y.)

Publication Date





1143 - 1146


Department of Biology, Johns Hopkins University, Baltimore, MD 21218.


Ovum, Animals, Sea Urchins, Calcium, Egtazic Acid, Adenosine Diphosphate Ribose, Cyclic ADP-Ribose, Adenosine Triphosphate, Spectrometry, Fluorescence, Kinetics, Time Factors