Repetitive stimulation increases the activation rate of skeletal muscle Ca2+ currents.

Voltage clamp experiments were conducted in frog skeletal muscle using repetitive stimulation protocols. The activation rate of Ca2+ currents increased by prepulses to depolarizing potentials or by stimulating the fiber with a frequency of 1.7 Hz at 0 mV. The effect was observable with Ca2+ or Ba2+ ions, and was clearly voltage-dependent. Physiologically, it is relevant that such activation rate increase can take place during a train of action potentials.