Gu Ruimin, Jin Yan, Zhai Yuanyuan, Yang Lei, Zhang Chengbiao, Li Wennan, Wang Lijun, Kong Shumin, Zhang Yunhong, Yang Baofeng, Wang Wen-Hui
Department of Physiology, Harbin Medical University, Harbin, China.
Kidney Int. 2008 Aug;74(4):478-85. doi: 10.1038/ki.2008.198. Epub 2008 May 21.
To study the inhibition of the inwardly rectifying basolateral 50 pS potassium channels by PGE(2) we performed patch-clamp studies on the basolateral membrane of the rat kidney thick ascending limb. PGE(2)'s effect was mimicked by the selective EP1- and EP3-receptor agonist, sulprostone, but was prevented by inhibiting protein kinase-C with calphostin-C. The mitogen-activated protein kinase inhibitor PD98059 (ERK) or SB203580 (p38) increased basal channel activity; however, while neither alone prevented the inhibitory effect of PGE(2), but using both of them together completely abolished PGE(2)'s effect on channel activity. Treatment with PGE(2) stimulated phosphorylation of both p38 and ERK in primary cultures of medullary thick ascending limb cells. The PGE(2)-mediated mitogen-activated protein kinase activation was not affected by indomethacin, but was completely blocked by calphostin-C. These studies show that inhibition of basolateral 50 pS potassium channels by PGE(2) is mediated by protein kinase-C, which in turn stimulates mitogen-activated protein kinases in the thick ascending limb of the rat kidney.
为了研究前列腺素E2（PGE2）对内向整流性基底外侧50 pS钾通道的抑制作用，我们对大鼠肾髓袢升支粗段的基底外侧膜进行了膜片钳研究。选择性EP1和EP3受体激动剂舒前列素可模拟PGE2的作用，但用钙磷蛋白C抑制蛋白激酶C可阻止其作用。丝裂原活化蛋白激酶抑制剂PD98059（细胞外信号调节激酶，ERK）或SB203580（p38）可增加通道的基础活性；然而，单独使用这两种抑制剂均不能阻止PGE2的抑制作用，但两者联合使用则可完全消除PGE2对通道活性的影响。用PGE2处理可刺激髓袢升支粗段细胞原代培养物中p38和ERK的磷酸化。PGE2介导的丝裂原活化蛋白激酶激活不受吲哚美辛影响，但可被钙磷蛋白C完全阻断。这些研究表明，PGE2对基底外侧50 pS钾通道的抑制作用是由蛋白激酶C介导的，而蛋白激酶C反过来又刺激大鼠肾髓袢升支粗段中的丝裂原活化蛋白激酶。
