Arachidonic acid inhibits K channels in basolateral membrane of the thick ascending limb
Arachidonic acid inhibits K channels in basolateral membrane of the thick ascending limb
复制标题
花生四烯酸抑制厚升肢基底外侧膜中的 K 通道
DOI：
10.1152/ajprenal.00002.2002
复制
发表时间：
2002-09-01
影响因子：
4.2
通讯作者：
Wang, WH
中科院分区：
文献类型：
--
作者：
Gu, RM;Wang, WH
采用膜片钳技术研究花生四烯酸（AA）对大鼠肾髓质厚升肢基底外侧K通道的影响。在金属tal基底外侧膜的细胞附着和内向外斑块中发现了一个向内整流的50-pS K通道。在自发细胞膜电位下，通道打开概率（P-o）为0.51，在30 mV超极化下，通道打开概率降至0.25。5mum AA的加入使细胞贴附斑块的通道活性（鉴定为NPo）从0.58降至0.08。AA对50-pS钾通道的影响是特异性的，因为10mum顺式-11,14,17-二十碳三烯酸对通道活性没有显著影响。为了确定AA的作用是由AA本身介导还是由其代谢物介导，我们研究了AA在吲哚美辛（环加氧酶抑制剂）或n -甲基磺酰基-12,12-二溴十二烷-11-氨基酰胺（细胞色素P-450单加氧酶抑制剂）存在下对通道活性的影响。抑制环加氧酶使通道活性从0.54提高到0.9。然而，吲哚美辛并没有消除AA对50-pS K通道的抑制作用。抑制细胞色素P-450代谢不仅使通道活性从0.49提高到0.83，而且完全消除了AA的作用。此外，DDMS的加入可以逆转AA对通道活性的抑制作用。AA的作用是由AA的细胞色素p -450依赖性代谢物介导的，这一观点也得到了观察结果的支持，即添加100 nM的20-羟基二碳四烯酸（AA在金属tal中的主要代谢物）可以模拟AA的作用。我们认为，AA抑制金属tal基底侧膜的50-pS K通道，AA的作用主要是通过AA的细胞色素p -450依赖性代谢物介导的。
We have used the patch-clamp technique to study the effect of arachidonic acid (AA) on the basolateral K channels in the medullary thick ascending limb (mTAL) of rat kidney. An inwardly rectifying 50-pS K channel was identified in cell-attached and inside-out patches in the basolateral membrane of the mTAL. The channel open probability (P-o) was 0.51 at the spontaneous cell membrane potential and decreased to 0.25 by 30 mV hyperpolarization. The addition of 5 muM AA decreased channel activity, identified as NPo, from 0.58 to 0.08 in cell-attached patches. The effect of AA on the 50-pS K channel was specific because 10 muM cis-11,14,17-eicosatrienoic acid had no significant effect on channel activity. To determine whether the effect of AA was mediated by AA per se or by its metabolites, we examined the effect of AA on channel activity in the presence of indomethacin, an inhibitor of cyclooxygenase, or N-methylsulfonyl-12,12-dibromododec-11- enamide (DDMS), an inhibitor of cytochrome P-450 monooxygenase. Inhibition of cyclooxygenase increased channel activity from 0.54 to 0.9. However, indomethacin did not abolish the inhibitory effect of AA on the 50-pS K channel. In contrast, inhibition of cytochrome P-450 metabolism not only increased channel activity from 0.49 to 0.83 but also completely abolished the effect of AA. Moreover, addition of DDMS can reverse the inhibitory effect of AA on channel activity. The notion that the effect of AA was mediated by cytochrome P-450-dependent metabolites of AA is also supported by the observation that addition of 100 nM of 20-hydroxyeicosatetraenoic acid, a main metabolite of AA in the mTAL, can mimic the effect of AA. We conclude that AA inhibits the 50-pS K channel in the basolateral membrane of the mTAL and that the effect of AA is mainly mediated by cytochrome P-450-dependent metabolites of AA.