Inhibitory effect of kanamycin on evoked transmitter release. Reversal by 3,4-diaminopyridine.

The effect of kanamycin (Kn) on evoked transmitter release was examined in frog end-plates in vitro. By a presynaptic action, Kn (0.02 to 1 mM) significantly reduced the amount of acetylcholine liberated by nerve stimulation. In addition to its presynaptic effects, Kn (0.96 mM) decreased the size of the miniature end-plate potentials possibly by acting at the postsynaptic level. 3,4-Diaminopyridine (4.5 microM) reversed the presynaptic effects of Kn but did not modify its postsynaptic action.