BACKGROUND: According to the report that KCNK activity in transfected COS-7 and HEK-293 cells was modulated by volatile anesthetics and activation of KCNK channels by neuroprotectants, the importance of KCNK2 were emphasized. In this study, we studied the effect of halothane and isoflurane on KCNK2 in the KCNK2 transfected HEK-293 cells.

METHODS: Multiple patch clamp experiments with halothane and isoflurane were conducted to characterize KCNK2 in the KCNK2 transfected HEK-293 cells. KCNK2 cDNA were transiently transfected with FuGENE6 transfection reagents and whole cell recordings were made using predesigned pulse protocol.

RESULTS: KCNK2 transfected HEK cells exhibited rapid rising, a time-independent, non-inactivating, outward-rectifying currents and had no threshold for activation by voltage. Multiple patch clamp experiments showed the presence of outward-rectifying K⁺ selective channels with a conductance of 1.31 ± 0.59 nS (n = 16) at positive potentials. Recordings of halothane 448µM (-2 MAC) increased outward currents from control by 218% in standard saline perfusate (n = 4, P<0.05, paired t-test) and that of isoflurane 822µM (-3 MAC) increased outward currents by 172% in standard saline perfusate (n = 12, P<0.05, paired t-test). Channel activity enhanced during the duration of the exposure to volatile anesthetics returned to the baseline quickly upon wash.

CONCLUSIONS: Considering the activation of KCNK2 by neuroprotectants such as riluzole and PUFA, we might think of the possibility of halothane and isoflurane as neuroprotectants because these anesthetics activated background K⁺ channels in KCNK2 transfected HEK-293 cells.