MULTIPLE CELLULAR AND SUBCELLULAR ACTIONS OF GENERAL-ANESTHETICS ON CULTURED MOLLUSCAN NEURONS

The pond snail Lymnaea stagnalis has been used as a model system to st udy the cellular and subcellular actions of general anaesthetics. Here we describe the actions of general anaesthetics mainly on cultured, i dentified neurones, maintained in isolation to prevent the actions of synaptic inputs upon them. Using the whole-cell patch-clamp technique, we have found that application of clinical concentrations of inhalati onal anaesthetics (halothane and isoflurane) and barbiturates depresse s whole-cell calcium currents and potassium currents in a concentratio n-dependent manner. After loading cultured neurones with the ratiofluo rescent dye fura-2AM, we find that halothane raises intracellular calc ium concentration in a concentration-dependent manner, both in the pre sence and absence of extracellular calcium. Thus anaesthetics have mul tiple cellular and subcellular actions, some of which we have describe d, but most of which are yet to be discovered.