BLOCK OF NICOTINIC ACETYLCHOLINE-ACTIVATED CHANNELS OF CULTURED MOUSEMYOTUBES BY ISOFLURANE

It is well known that volatile anesthetics cause muscle relaxation. A block of nicotinic acetylcholine-activated receptors (nAChRs) in staed y state by isoflurane was recently reported. Pulses of acetylcholine ( ACh) were applied to outside-out patches from mouse myotubes using a s ystem for ultra-fast solution exchange allowing the study of the block of nAChRs by isoflurane under conditions similar to the situation dur ing synaptic transmission. Isoflurane in concentrations used during ge neral anesthesia blocked similar to 50% of the receptors within 0.5 ms after application. The block of nAChRs could be partially relieved by application of high concentrations of ACh. Therefore, muscle relaxati on and the reduction of the amplitude of postsynaptic currents by isof lurane may be caused by the block of nAChRs reported here.