ACTH-(4-10) INCREASES QUANTAL CONTENT AT THE MOUSE NEUROMUSCULAR-JUNCTION

Adrenocorticotropic hormone 4-10 (ACTH 4-10), in concentrations of 50 nM and 1 mu M, increased both the frequency of miniature endplate potentials and the amplitude of the endplate potentials in addition to decreasing the number of failures following stimulation of the phrenic nerve in the mouse in vitro. There was no effect of the peptide on either the amplitude of the miniature endplate potentials or the resting membrane potential of the muscle fibres. These results indicate that the action of ACTH 4-10 was to increase the quantal content of the endplate potential via a presynaptic action.