Bromo-eudistomin D, a novel inducer of calcium release from fragmented sarcoplasmic reticulum that causes contractions of skinned muscle fibers

Y. Nakamura, J. Kobayashi, Jeremy Gilmore, Mark Mascal, Kenneth L. Rinehart, H. Nakamura, Y. Ohizumi

Research output: Contribution to journalArticle

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Abstract

Bromo-eudistomin D induced a contraction of the chemically skinned fibers from skeletal muscle at concentrations of 10 μM or more. This contractile response to bromo-eudistomin D was completely blocked by 10 mM procaine. The extravascular Ca2+ concentrations of the heavy fractions of the fragmented sarcoplasmic reticulum (HSR) were measured directly by a Ca2+ electrode to examine the effect of bromo-eudistomin D on the sarcoplasmic reticulum. After the HSR was loaded with Ca2+ by the ATP-dependent Ca2+ pump, the addition of 10 μM bromo-eudistomin D caused Ca2+ release that was followed by spontaneous Ca2+ reuptake. In the presence of 2 μM ruthenium red or 4 mM MgCl2, no Ca2+ release was induced by 20 μM bromo-eudistomin D. The rate of 45Ca2+ efflux from HSR, which had been passively preloaded with 45Ca2+, was accelerated 7 times by 10 μM bromo-eudistomin D. The concentration of bromo-eudistomin D for half-maximum effect on the apparent efflux rate was 1.5 μM, while that of caffeine was 0.6 mM. The bromo-eudistomin D-evoked efflux of 45Ca2+ was abolished by 2 μM ruthenium red or 0.5 mM MgCl2. Bromo-eudistomin D was found to be 400 times more potent than caffeine in its Ca2+-releasing action but was similar in its action in other respects. These results indicate that bromo-eudistomin D may induce Ca2+ release from the sarcoplasmic reticulum through physiologically relevant Ca2+ channels.

Original languageEnglish (US)
Pages (from-to)4139-4142
Number of pages4
JournalJournal of Biological Chemistry
Volume261
Issue number9
StatePublished - 1986
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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    Nakamura, Y., Kobayashi, J., Gilmore, J., Mascal, M., Rinehart, K. L., Nakamura, H., & Ohizumi, Y. (1986). Bromo-eudistomin D, a novel inducer of calcium release from fragmented sarcoplasmic reticulum that causes contractions of skinned muscle fibers. Journal of Biological Chemistry, 261(9), 4139-4142.