Acceleration by stannous ion of the evoked release of transmitter from motor nerve endings in the frog.

Stannous ion (Sn2+, 30 microM) increased the amplitude of endplate potential (EEP) in the frog sartorius muscle, although the amplitude of miniature endplate potential (MEPP) or acetylcholine potential evoked by iontophoretic application of acetylcholine was unchanged. Sn2+ (10-100 microM) dose-dependently increased the quantal content of the EPP. MEPP frequency was not altered by 30 microM Sn2+. These findings indicate that Sn2+ may increase the EPP as a result of acceleration of the transmitter release evoked by nerve impulses.