Denervation supersensitivity: the response to depolarizing muscle relaxants.

The chemical theory of neuromuscular transmission (Dale, Feldberg and Vogt, 1936) is now almost universally accepted, and implicates acetylcholine as the neuromuscular transmitter. Depolarizing muscle relaxants act, at least initially, in a manner similar to acetylcholine and are believed to produce their effects by prolonged depolarization, but in certain situations these agents, instead of producing muscular paralysis, cause an increase in muscle tension. One such situation is seen with denervated muscle. That contracture can occur in denervated and partially denervated muscles following acetylcholine and acetylcholine-like substances has been known to the physiologist for a long time (Dale and Gasser, 1926). Reports of this occurrence, however, during anaesthesia are scarce (Marshall, 1964; Wylie and Churchill Davidson, 1972) and the mechanism is obscure.