MODIFICATION BY DRUGS USED IN ANAESTHESIA OF CNS STIMULATION INDUCED IN MICE BY LAUDANOSINE AND STRYCHNINE

We have investigated in mice the effects of several drugs whichmay be administered as part of an anaesthetic technique on theconvulsive threshold to laudanosine and to strychnine, whichis reported to have a similar mechanism of action, l.v. administeredpropofol, thiopentone and midazolam increased the dose of convulsantnecessary to produce seizure when administered 2 min beforethe convulsive stimulus. In contrast, methohexitone and etomidateexhibited a pro-convulsant effect, although with the latterthis was significant only in laudanosine-treated mice. Pethidinewas proconvusant in both laudanosine- and strychnine-treatedmice, but morphine was proconvusant only in strychnine-treatedmice. The effects of morphine, but not pethidine, were antagonizedby naloxone 1 mg kg^–1. Laudanosine, but not strychninecaused arousal from anaesthesia in subconvulsive doses. Thisand other evidence suggests that the mechanism of the CNS excitationproduced by strychnine and laudanosine are not the same. Communicated in pan to the Anaesthetic Research Society, November1990.