HALOTHANE ALTERS ELECTRICAL-ACTIVITY AND CALCIUM DYNAMICS IN CULTUREDMOUSE CORTICAL, SPINAL-CORD, AND DORSAL-ROOT GANGLION NEURONS

Halothane inhibits neural plasma membrane Ca2+-ATPase, a pump that eje cts Ca2+ from the cell after influx through voltage- or ligand-activat ed channels. Intracellular microelectrode recordings in mouse embryoni c cortical and spinal cord neurons showed that halothane and eosin, a pump inhibitor, prolonged repolarization associated with spontaneous b ursts of depolarization. These agents also prolonged the repolarizatio n phases of electrically induced action potentials and of capsaicin-me diated Ca2+-dependent depolarization in mouse adult dorsal root gangli on neurons. In keeping with these findings, confocal microfluorimetry showed that halothane delayed clearance of intracellular Ca2+ accumula ted by N-methyl-D-aspartate stimulation of single neurons.