The influence of cold on the recovery of three neuromuscular blocking agents in man

The Arrhenius hypothesis suggests that change in temperature has a less marked effect on the rate of physical processes than on biological reactions. We have investigated the process underlying recovery from neuromuscular block in man by studying the effect of cooling on the rate of recovery from depolarising and non-depolarising block. Vecuronium, rocuronium and decamethonium (C10) neuromuscular block were investigated using the isolated forearm technique on awake human volunteers. In these experiments, one arm was cooled whilst the other was used as control. Moderate hypothermia decreased the rate of recovery from all three agents, but this was significantly less marked with the depolarising drug. The mean Q10 (the anticipated change in rate of a reaction across of 10 degrees C temperature gradient) of the rate of recovery for vecuronium was 3.21, rocuronium 2.86 and decamethonium 1.29. This suggests a different process in the recovery of these two types of drug. According to the Arrhenius hypothesis this would suggest that the recovery from non-depolarising drugs is likely to involve a biochemical mechanism and that recovery from decamethonium is controlled by a physical process.