GENERAL ANAESTHETICS AND THE ACETYLCHOLINE‐SENSITIVITY OF CORTICAL NEURONES

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Abstract
The effects of general anaesthetics on neuronal responses to iontophoretically‐applied acetylcholine have been examined in slices of guinea‐pig olfactory cortex maintained in vitro. Acetylcholine excited 61% of the prepiriform neurones tested. The excitation was blocked by atropine, but not by dihydro‐β‐erythroidine or gallamine. Alphaxalone reversibly depressed the acetylcholine‐sensitivity of prepiriform neurones. Pentobarbitone did not consistently depress the acetylcholine sensitivity of these cells. Ether, methoxyflurane, trichloroethylene and halothane caused a dose‐related augmentation of acetylcholine‐induced firing. These results show that general anaesthetics do not necessarily depress the sensitivity of nerve cells to all excitatory substances and that different anaesthetics may affect a particular excitatory process in various ways.