The effect of inhalational anaesthetics on the microtubular system in Actinosphaerium nucleofilum

Six different anaesthetic agents were found to cause reversible collapse of the axopods of Actinosphaerium nucleofilum. The effect occurred at concentrations proportional to those required to anaesthetize man. Electron microscopy showed dispersal of the microtubular system and disaggregation of the microtubules of the axonemes, and expanded microtubules without interlinkage were seen in the related heliozoon Actinophrys sol under treatment with halothane. In both genera there was a rapid reassembly during the recovery period. Diethyl ether, an inhalational anaesthetic with a particularly large molecule, was ineffective except at relatively very high concentrations, and with this agent cytolysis often occurred with little or no shortening of axopods.