Anions that potentiate excitation-contraction coupling may mimic effect of phosphate on Ca2+ release channel

B. R. Fruen, J. R. Mickelson, T. J. Roghair, H. L. Cheng, C. F. Louis

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Perchlorate is one of a group of inorganic anions that potentiate excitation-contraction coupling in skeletal muscle. We have compared the effect of perchlorate on the sarcoplasmic reticulum (SR) Ca2+-release channel with the effect of inorganic phosphate (P(i)), an anion which accumulates in skeletal muscle during exercise. Perchlorate and P(i) (10-20 mM) stimulated Ca2+ release from SR vesicles 2- to 3-fold, respectively, and increased ryanodine binding to SR vesicles 1.5-fold. Stimulation of SR Ca2+-release channel activity by both perchlorate and P(i) was maximal in the presence of micromolar Ca2+ and was associated with an increased affinity of the channel for ryanodine. Other anions known to potentiate muscle contraction (thiocyanate, iodide, and nitrate) also stimulated skeletal muscle SR Ca2+ release and ryanodine binding, as did the P(i) analogue vanadate. However, none of the inorganic anions examined altered ryanodine binding to cardiac muscle SR. These results confirm that the SR Ca2+-release channel may be a primary site at which perchlorate and other potentiating anions affect skeletal muscle excitation-contraction coupling. In addition, these results demonstrate that the action of these anions on the SR Ca2+-release channel resembles that of P(i), a potential endogenous regulator of this channel.

Original languageEnglish (US)
Pages (from-to)C1729-C1735
JournalAmerican Journal of Physiology - Cell Physiology
Issue number6 35-6
StatePublished - 1994


  • inorganic phosphate
  • perchlorate
  • ryanodine receptor
  • sarcoplasmic reticulum
  • vanadate


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