纳他卡林激活内皮细胞ATP敏感性钾通道SUR2B/Kir6.1亚型对eNOS磷酸化的调节作用

Regulation of eNOS phosphorylation by natakalim via activating ATP-sensitive potassium channel subtype SUR2B /Kir6. 1 in endothelial cells

目的 纳他卡林可选择性激活ATP敏感性钾通道（Katp）SUR2B／Kir6．1亚型，引起胞内ca2＋’浓度升高，一氧化氮合酶（eNOS）活性增强，NO释放增加。eNOS活性与eNOS磷酸化密切相关，研究表明eNOS-Serll77、eNOS-Ser635、eNOS-Set615磷酸化增强eNOS活性，eNOS-Thr495、eNOS-Serl16磷酸化抑制eNOS活性。本文研究纳他卡林激活Km对eNOS各磷酸化位点的影响，以此认识纳他卡林增强eNOS活性的作用特点。方法在培养的内皮细胞上给予（1）10^-9-10^-9mol·L^-1不同浓度的纳他卡林孵育5min，（2）预孵育0．01-1μmol·L。格列苯脲30min，给予1肛mol·L^-1纳他卡林孵育5rain，提取细胞总蛋白，用Western blot法检测eNOS-Serl177、eNOS-Ser635、eNOS-Set615、eNOS-Thr495、eNOS．Serll6磷酸化的变化。结果纳他卡林可浓度依赖性的升高eNOS．Serll77、eNOS，Ser635的磷酸化及eNOS．Thr495的去磷酸化，而对eNOS-Ser615和eNOS-Serl16磷酸化无影响。此作用可被K。特异性阻断剂格列苯脲拮抗。结论纳他卡林通过激活内皮细胞Katp，调节eNOS-Serll77、eNOS．Ser635的磷酸化及eNOS-Thr495的去磷酸化，但不影响eNOS-Ser615和eNOS-Serl16磷酸化，从而增强eNOS活性。

Aim Natakalim activates SUR2B/Kir6. 1 subtype of KAye selectively to increase intracellular Ca2 ＋ concentration , expression of （eNOS） , and NO re-lease. While phosphorylation of Ser615, 635, and 1177 results in the activation of eNOS and the phos-phorylation of Serll6 and Thr495 reduces the eNOS function. To observe the regulative effects of natakalim on eNOS phosphorylation. Methods （ 1 ） The cul-tured EA. hy926 endothelial cells were treated with na- takalim at the concentrations of 10-9 _ 10-5 mol . L-l for 5 rain; （2）cells were pre-incubated with glib-enclamide at the concentrations of 0.01 - 1 p, mol. L- 1 for 30 rain and then treated with 1 p, mol . L-1 natakal-im for 5 min. The total protein was extracted and theeNOS phosphorylation of Ser1177, Ser635, Thr495, Ser116 and Ser615 was examined by Western blot anal-ysis. Results Natakalim dose-dependently enhanced the phosphorylation of eNOS at Ser1177 and Ser635, decreased the phosphorylation of eNOS at Thr495, but had no effects on Serll6 and Ser615 residues in endo-thelial cells. These modulations could all be blocked by glibenclamide. Conclusion Natakalim increases the phosphorylation of Serl177, Ser635 and de-phos-phorylation of Thr495 to enhance eNOS activity via the activation of endothelial KATP channels.