THE EFFECT OF CARBON DIOXIDE ON NEUROMUSCULAR TRANSMISSION

Abstract

It has long been known that the neuromuscular junction is very sensitive to carbon dioxide and the transmission across this junction is easily blocked under the effect of this gas. The aim of the present experiment is to clarify the underlying mechanism of this blockage by analysing the effects of carbon dioxide on the pre- and postsynaptic elements. According to the chemical transmission hypothesis (1) (2), the impulse in the motor nerve fiber on reaching the terminals causes acetylcholine, the transmitter, to be released there . This substance diffuses to and reacts with the receptor in the surface of end-plate . The reaction occuring between the receptor and the transmitter alters the physicochemical properties of the surface membrane of end-plate and consequently induces the excitation of muscle membrane. It was clarified in this study that although the sensitivity of end-plate membrane to acetylcholine is considerably increased by the effect of carbon dioxide, the neuromuscular transmission is blocked on account of the failure in impulse conduction at the motor nerve terminals.