Effects of volatile anesthetic isoflurane on ATP-sensitive K+ channels in rabbit ventricular myocytes

It has been suggested that volatile anesthetic. isoflurane mediates cardioprotective effects via activation of the ATP-sensitive K+ (K-ATP) channels. However, no direct evidence has been provided to define whether isoflurane activates cardiac K-ATP channels using patch-clamp technique. We examined the effects of isoflurane on the K-ATP channels in rabbit ventricular myocytes by use of patch-clamp technique. Contrary to the results of the in vivo experiments, isoflurane inhibited the channel activity without a change in the single-channel conductance. Isoflurane decreased the channel activity by a decrease in burst duration and an increase in the inter-burst duration. On the other hand, isoflurane diminished the ATP sensitivity of K-ATP channels, indicating an increased probability of K-ATP channel opening for a given concentration of ATP after isoflurane anesthesia. The result supports, at least in part, the hypothesis that isoflurane mediates cardioprotective effects via K-ATP channel activation. (C) 1996 Academic Press.