Effects of calcium blockers on the discharge pattern of frog muscle spindle.

Abstract Application of calcium blockers, such as MnCl 2 , MgCl 2 , EGTA and verapamil, resulted in a decrease in the dynamic response of afferent discharges during ramp-and-hold stretch of the frog muscle spindle, causing mainly the reduction of the peak rate at the completion of the stretch. As calcium spikes in the spindle terminal have been known to superimpose preferably at the completion of ramp stretch, it is suggested that a part of the dynamic response of afferent discharges is possibly contributed by the calcium spike in the terminal.