THE SUMMATION OF FACILITATING AND INHIBITORY EFFECTS AT THE MAMMALIAN NEUROMUSCULAR JUNCTION

Abstract

In the curarized mammal, tetanic stimulation of a motor nerve results in (a) a brief phase of facilitation (the classical latent addition), (b) Wedensky inhibition, (c) a second, prolonged phase of facilitation. At the neuromuscular junction facilitating and inhibitory processes can coexist, the former being masked by, but outlasting, the latter. If Mg be substituted for curare the 2 phases of facilitation are still demonstrable but overlap in time, Wedensky inhibition being absent. Hypotheses advanced to account for these phenomena are briefly discussed.