BLOCK OF NICOTINIC ACETYLCHOLINE-ACTIVATED CHANNELS OF CULTURED MOUSE MYOTUBES BY ISOFLURANE

It is well known that volatile anesthetics cause muscle relaxation. A block of nicotinic acetylcholine-activated receptors (nAChRs) in staedy state by isoflurane was recently reported. Pulses of acetylcholine (ACh) were applied to outside-out patches from mouse myotubes using a system for ultra-fast solution exchange allowing the study of the block of nAChRs by isoflurane under conditions similar to the situation during synaptic transmission. Isoflurane in concentrations used during general 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 relaxation and the reduction of the amplitude of postsynaptic currents by isoflurane may be caused by the block of nAChRs reported here.