Effects of Intravenous and Intra‐arterial Procaine and Lidocaine on Neuromuscular Transmission in Man

1 The effects of procaine and lidocaine on neuromuscular transmission were determined in man. 2 These agents when injected intravenously did not decrease the twitch response. However, if a partial neuromuscular block was produced by succinyl-choline or d-tubocurarine, the block was increased by procaine or lidocaine. 3 A neuromuscular blocking action of procaine and lidocaine could be demonstrated following intra-arterial injection. 4 A decrease in respiration or apnea could be produced by doses of procaine and lidocaine which did not depress neuromuscular transmission. 5 It was suggested that although local anesthetic agents may affect the motor nerve terminal, the release of ACh, and skeletal muscle directly, at present the neuromuscular blocking activity of local anesthetics appears to be attributable mainly to their acetylcholine inhibiting action at the motor end plate.