依托咪酯对新生大鼠皮质神经元钙激活性钾通道的作用

Effects of Etomidate on Single Calcium-activated Potassium Channel inNeonatal Rat Sensory Contex Neurones

采用膜片钳技术（ｐａｔｃｈｃｌｍａｐｔｅｃｈｎｉｑｕｅ）的吸附式（ｃｅｌｌ－ａｔｔａｃｈｅｄ）和内面向外式（ｉｎｓｉｄｅ－ｏｕｔ）两种构型研究了依托咪酯对培养的ＳＤ新生鼠皮质神经元钙激活性钾（ＫＣａ）通道的作用。结果：①新生ＳＤ大鼠皮质神经元上存在有单位电导为１７６．６５±３７．９７ｐＳ（ｎ＝１２）的ＫＣａ通道；②依托咪酯（ｕｍｏｌ／Ｌ）０．８、４、１０、２０四个不同剂量在吸附式构型时浓度依赖性激活ＫＣａ通道，其开放概率（Ｐｏ）较对照组均明显增大（Ｐ＜０．０１，ｎ＝６）：③依托咪酯０．８ｕｍｏｌ／Ｌ在内面向外式构型时对ＫＣａ通道也有明显激活作用，Ｐｏ增大（Ｐ＜０．０１，ｎ＝４）．结果提示：依托咪酯明显激活ＫＣａ通道，其直接作用于通过蛋白或通道周围膜，这可能是其麻醉机制的一部分。

The effects of etomidate on single calcium-activated potassium (KCa) channel incultured rat sensory cortex neurons were studied using cell-attached and inside-out patch clamp.The results showed that: l . This KCa channel has a slop conductance of 176.65+37.97pS(n=12)under symmetrical high K+ (140mmol/L) solution.2.In cell-attached patches, etomidate 0.8, 4,l0 and 20 Pmol/L respectively i significantly the calcium-activated potassium channels in a concentra-tion-dependent manner. The open probability (Po) increased markedly (P<0.01, n=4).3.In inside-out patches,etomidate 0.8umol/L also significantly activated this channel and increased the openingprobability (P<0.01,n=3).These results indicated that etomidate activated the KCa. channels markedly,and affected KCa. channels or its peripheral membrane directly. It could be related possibly to themechanism of etomidate anesthesia.