Current data on curarization

The knowledge of the mechanism of action of neuromuscular blocking agents has improved together with the better understanding of the physiology of the neuromuscular junction at the molecular and cellular levels. The main action of competitive neuromuscular relaxants is the blockade of the acetylcholine binding site of the acetylcholine receptor when the latter is its inactive-closed conformation. Owing to the high margin of safety of the neuromuscular transmission, the blockade of an important fraction (75-90%) of acetylcholine receptors is necessary to cause a decrease in muscle strength. An other mechanism of action of competitive agents is the blockade of presynaptic secretion of acetylcholine during repetitive stimulations which may explain the phenomenon of train of four fade or of tetanic fade.