[The presynaptic action of muscle relaxants and cholinesterase inhibitors]

This is a review of literature dealing with the action of relaxants and cholinesterase inhibitors on the skeletal muscles. They act on the presynaptic motor nerve endings in the muscles and, depending on the experimental conditions, increase or inhibit the release of acetylcholine by the endings. According to the literature data, two types of acetylcholine receptors (AchR) exist on the endings of a motor nerve. The neuronal type of AchR is related to a negative feedback mechanism and their blockade increases the release of acetylcholine by the motor nerve ending. Blockade of the muscular-type AchR is related to a positive, feedback mechanism and inhibits the release of acetylcholine.