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Ryanodine Activates Sea Urchin Eggs
Author(s) -
Sardet C.,
Gillot I.,
Ruscher A.,
Payan P.,
Girard J.P.,
Renzis G.
Publication year - 1992
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1992.00037.x
Subject(s) - ryanodine receptor , sea urchin , ruthenium red , calcium , digitonin , endoplasmic reticulum , calcium in biology , biology , chemistry , biophysics , microbiology and biotechnology , biochemistry , enzyme , organic chemistry
We have studied the effect on sea urchin eggs of ryanodine, a plant alkaloid that causes muscle contraction by opening calcium channels in the sarcoplasmic reticulum terminal cisternae. Ryanodine, although it is less effective that IP 3 , produces full or partial activation in 62% of injected sea urchin eggs. In addition ryanodine inhibits in a dose dependant manner 45 Ca pumping in the isolated egg cortex or in eggs permeabilized with digitonin. Efflux experiments show that in fact ryanodine as IP 3 stimulates the release of calcium sequestered intracellularly. We further show that these effects of ryanodine are inhibited by Mg ++ , ruthenium red and heparin. Our results suggest that ryanodine‐sensitive intracellular calcium channels exist in the sea urchin egg.