Effects of rate of stimulation and of fatigue on the response to neuromuscular blocking agents.

The response to neuromuscular blocking agents, as exemplified by suxamethonium and tubocurarine, may differ between symmetrical muscles. Increased rates of stimulation and fatigue both increase sensitivity to blocking agents. During recovery from suxamethonium block muscles may show a transitory failure to react to each stimulus with a contraction. Fatigue caused by prolonged indirect stimulation is prevented equally well by suxamethonium and tubocurarine in doses producing a complete block. The mechanism and significance of these findings are discussed.