Ca2+-Induced Ca2+ Release in Sea Urchin Egg Homogenates: Modulation by Cyclic ADP-Ribose
Abstract
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 Ca2+-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.
- Publication:
-
Science
- Pub Date:
- September 1991
- DOI:
- 10.1126/science.1909457
- Bibcode:
- 1991Sci...253.1143G