The Japanese Journal of Physiology
Print ISSN : 0021-521X
Relationship between Membrane Potential and Calcium Ion Fluxes in the Fragmented Sarcoplasmic Reticulum
越田 信堀田 健
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1981 年 31 巻 1 号 p. 109-120

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The relation between membrane potential and Ca2+fluxes in the skeletal fragmented sarcoplasmic reticulum (FSR) was investigated using cyanine dye (diS-C3-(5)) as a potential probe.Change of membrane potential and Ca2+release from FSR were induced by changing the ionic composition of the medium.
When the medium was changed from K-gluconate to Tris-gluconate, a large fluorescence intensity change was observed, while no Ca2+release occurred.On the other hand, when the medium was changed from K-gluconate to KCl, Ca2+release occurred notwithstanding a relatively small fluorescence intensity change.This KCl-induced Ca2+release from FSR was inhibited by the addition of sucrose.Also, the presence of both permeable anion and cation was required for induction of Ca2+ release. These results suggest that there is no correlation between “depolarization” and Ca2+release.
Ca2+uptake by FSR created the positive-inside potential which was reversed by the application of Cat+ionophore A23187.The addition of valinomycin or nigericin, and the replacement of Cl-with gluconate-affected potential formation.These facts suggest that Cat+uptake is accompanied by K+efflux and/or Cl-influx for partial compensation of the change.
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© Physiological Society of Japan
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