SEVOFLURANE-INDUCED IONIC CURRENT IN ACUTELY DISSOCIATED CA1 PYRAMIDAL NEURONS OF THE RAT HIPPOCAMPUS

The electrophysiological properties of sevoflurane (Sev)-induced curre nt (I-Sev) were investigated in CAl pyramidal neurons freshly dissocia ted from the rat hippocampus by using the nystatin perforated patch re cording configuration under voltage-clamp condition. Within the range of Sev concentrations from 3.10(-4) to 2.10(-3) M, I-Sev was an inward current which consisted of an initial transient peak component and a successive steady-state plateau component. The peak current component increased in a concentration-dependent manner with a conductance incre ase. The application of Sev over 2.10(-3) M, however, suppressed the p eak and steady-state current components with a concomitant decrease in conductance and elicited a transient inward current ('hump' current) immediately after wash out. The current-voltage relationship for I-Sev showed some outward rectification suggesting a slight voltage-depende ncy of the: I-Sev. The reversal potential of I-Sev (E(Sev)) was close to the E(Cl) and shifted by 52 mV for a 10-fold change in extracellula r Cl- concentrations, indicating that I-Sev is passing through Cl- cha nnels. The single channel conductance obtained from the analysis of th e variance of I-Sev fluctuations was 15.3 +/- 1.3 pS.