Mechanism of Ca2+ release in medaka eggs microinjected with inositol 1,4,5-trisphosphate and Ca2+.
The reaction time of Ca2+ release from cytoplasmic stores induced by microinjection of inositol 1,4,5-trisphosphate (IP3), calcium ionophore A23187, Ca2+, Sr2+, Ba2+, and cyclic guanosine 5'-monophosphate (cGMP) in Oryzias latipes eggs in Ca2+-free medium was measured by the luminescence of aequorin injected into the egg. Microinjection of IP3 or calcium ionophore induced rapid Ca2+ release without a time lag, while microinjection of either Ca2+ or cGMP required a time lag of 5-30 sec for Ca2+ release. Following microinjection of both IP3 and Ca2+, Ca2+ release commenced in a cytoplasmic region close to the egg surface. These results suggest that in the medaka egg, cytoplasmic Ca2+ induces Ca2+ release from cytoplasmic stores indirectly, probably via a membrane factor such as IP3.
Iwamatsu
T
T
Department of Biology, Aichi University of Education, Kariya, Japan.
Yoshimoto
Y
Y
Hiramoto
Y
Y
D000331:Aequorin; D000818:Animals; D001464:Barium / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D003532:Cyprinodontiformes / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005089:Exocytosis; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D007700:Kinetics; D008163:Luminescent Measurements; D008845:Microinjections; D009990:Oryzias / Q000378:metabolism*; D010063:Ovum / Q000187:drug effects / Q000378:metabolism*; D013324:Strontium / Q000494:pharmacology; D013403:Sugar Phosphates / Q000494:pharmacology*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D001464:Barium; D000001:Calcimycin; D000331:Aequorin; D015544:Inositol 1,4,5-Trisphosphate; D006152:Cyclic GMP; D002118:Calcium; D013324:Strontium