INHIBITION BY LEAD OF THE CALCIUM PLATEAU CURRENT AT MOUSE MOTOR-NERVE ENDINGS

THE inhibition by lead of motor terminal calcium plateau signals has b een studied using extracellular, perineuronal electrodes applied to th e M. triangularis sterni preparation of the mouse. The long-lasting ca lcium pateau signal induced by 3,4-DAP (250 mu mol) and TEA (10 mmol) blockade of presynaptic potassium channels was irreversibly blocked by micromolar lead concentrations in a concentration-dependent manner. T hese results suggest that lead antagonizes neuronal calcium channels i nvolved in transmitter release from motor nerve terminals.