Non-volatile general anaesthetics reduce spinal activity by suppressing plateau potentials

Non-volatile general anaesthetics are thought to reduce brain activity by potentiating inhibitory GABA(A) receptor channels but also cause adverse effects by suppressing L-type calcium channels in the heart. In sections of the spinal cord, the non-volatile anaesthetics pentobarbital, thiopental and propofol reduced excitability of sensorimotor neurons by suppressing plateau potentials mediated by L-type calcium channels. This effect mas independent of GABA(A) receptor potentiation but occurred in an overlapping concentration range, Therefore, the suppressive effect of non-volatile anaesthetics on L-type calcium channels can contribute to the reduction of spinal sensorimotor activity during anaesthesia, The results support the idea that general anaesthesia is achieved through several mechanisms and suggest that procedures for anaesthesia mag. be improved by combining selective agents for each mechanism rn optimal concentrations. (C) 1998 IBRO. Published by Elsevier Science Ltd.