Effect of Bromide Ions on Junctional Transmission

Abstract

Muchnik and Gage¹ have recently suggested that bromides act as sedatives by reducing the amount of transmitter substances released at synapses in the central nervous system. The evidence in favour of this suggestion is that the replacement of external chloride by bromide ions reduces the quantal content of the end-plate potential (e.p.p.) of frog skeletal muscle fibres. This result, however, was obtained in experiments in which neuromuscular transmission was already blocked, and the quantal content of the e.p.p. greatly reduced, by the presence of magnesium ions and a subnormal concentration of calcium ions. It therefore seemed of interest to investigate the action of bromide ions on synaptic transmission in an otherwise normal ionic environment.