How perchlorate improves excitation-contraction coupling in skeletal muscle fibers.

The effect of the "chaotropic" anion, perchlorate, on the activation of contraction has been studied in voltage clamped frog skeletal muscle fibers. It was found that the voltage dependence of either the contractile force or the intramembrane charge movement was shifted towards more negative membrane potentials. The maximum values of force or charge movement attained with large depolarizing pulses did not change significantly. It is concluded that a specific perchlorate effect on the movement of charged particles can explain the potentiating effect of perchlorate anions on contractile force, strengthening the view that these charged particles serve as voltage sensors regulating Ca2+ release from the sarcoplasmic reticulum.