Studies of the interaction of anaesthetics with various preparations, from whole animals to organic solvents, have been continuing since Overton and Meyer found a correlation between anaesthetic potency and solubility in olive oil. Although the physiological basis of anaesthesia is far from clear, one popular hypothesis is that anaesthetics act primarily by interfering with the normal functioning of chemical synapses. This hypothesis is supported by experiments showing that these synapses are more sensitive to both local and general anaesthetics than are axons. The effects of anaesthetics on electrical synapses (gap-junctions or nexus) have not previously been studied. These ubiquitous structures, presumably responsible for cell-to-cell communication, are found in most vertebrate and invertebrate tissues. We report here the effects of several anaesthetics on electronic coupling between nerve cells, and show that electrical synapses are less sensitive to most anaesthetics than are chemical synapses and axonal membranes.

SUMMARYWe have developed a technique for cannulation and internal perfusion of crayfish segmented lateral axons. Experiments on perfused and non-perfused axons lead to the following conclusions:1. Internally perfused segmented axons behave very similarly to non-perfused axons.2. The axial electrical resistance of the junctional region is almost as low as a comparable segment of axon.3. Neither intracellular Ca2+ nor H+ is effective in disrupting the intercellular communication pathway in perfused axons.On the basis of these findings we have formulated a hypothesis for cellular control of intercellular coupling based on the existence of a soluble intermediate for Ca2+ or H+-induced uncoupling. This hypothesis is consistent with data from both internally perfused and non-perfused axons.

the description of electrotonic coupling between 'lateral axons of the crayfish nerve cord (Watanabe and Grundfest, 'l961),-this synapse has shown no sign of being other than a linear current pathway. Electrotonic junctions from other systems studied over a period of many years also 'behave as linear pathways: pancreatic acinar cells