Obata Toshio
Department of Analytical Chemistry, School of Pharmaceutical Sciences, Ohu University, Koriyama, Fukushima 963-8611, Japan.
Anal Biochem. 2006 Sep 1;356(1):59-65. doi: 10.1016/j.ab.2006.06.018. Epub 2006 Jun 30.
The current study examined whether opening of the ATP-sensitive K(+) (K(ATP)) channel can induce hydroxyl free radical (OH) generation, as detected by increases in nonenzymatic formation of 2,3-dihydroxybenzoic acid (DHBA) levels in the rat myocardium. When KCl (4-140mM) was administered to rat myocardium through microdialysis probe, the level of 2,3-DHBA increased gradually in a potassium ion concentration (K(+))-dependent manner. The K(+) for half-maximal effect of the level of 2,3-DHBA production (ED(50)) was 67.9microM. The maximum attainable concentration of the level of 2,3-DHBA (E(max)) was 0.171microM. Induction of glibenclamide (10microM) decreased OH formation. The half-maximal inhibitory effect (IC(50)) for glibenclamide against the K(+) (70mM)-evoked increase in 2,3-DHBA was 9.2microM. 5-Hydroxydecanoate (5-HD, 100microM), another K(ATP) channel antagonist, also decreased K(+)-induced OH formation. The IC(50) for 5-HD against the K(+) (70mM)-evoked increase in 2,3-DHBA was 107.2microM. The heart was subjected to myocardial ischemia for 15min by occlusion of left anterior descending coronary artery (LAD). When the heart was reperfused, the normal elevation of 2,3-DHBA in the heart dialysate was not observed in animals pretreated with glibenclamide (10microM) or 5-HD (100microM). These results suggest that opening of cardiac K(ATP) channels by depolarization evokes OH generation.
本研究检测了ATP敏感性钾（K(ATP)）通道开放是否能诱导羟自由基（OH）生成，这可通过大鼠心肌中2,3 - 二羟基苯甲酸（DHBA）非酶促生成水平的增加来检测。当通过微透析探针向大鼠心肌施用氯化钾（4 - 140mM）时，2,3 - DHBA水平以钾离子浓度（K(+)）依赖性方式逐渐升高。2,3 - DHBA生成水平（ED(50)）的半数最大效应的K(+)为67.9μM。2,3 - DHBA水平的最大可达到浓度（E(max)）为0.171μM。给予格列本脲（10μM）可减少OH生成。格列本脲对K(+)（70mM）诱发的2,3 - DHBA增加的半数最大抑制效应（IC(50)）为9.2μM。另一种K(ATP)通道拮抗剂5 - 羟基癸酸（5 - HD，100μM）也可减少K(+)诱导的OH生成。5 - HD对K(+)（70mM）诱发的2,3 - DHBA增加的IC(50)为107.2μM。通过结扎左前降支冠状动脉（LAD）使心脏遭受15分钟的心肌缺血。当心脏再灌注时，在预先用格列本脲（10μM）或5 - HD（100μM）处理的动物中未观察到心脏透析液中2,3 - DHBA的正常升高。这些结果表明，去极化引起的心脏K(ATP)通道开放可诱发OH生成。
