Arachidonic acid inhibits activity of cloned renal K+ channel, ROMK1.
Arachidonic acid inhibits activity of cloned renal K+ channel, ROMK1.
复制标题
花生四烯酸抑制克隆肾 K 通道 ROMK1 的活性。
DOI：
10.1152/ajprenal.1996.271.3.f588
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Wang,WH
中科院分区：
文献类型：
--
作者：
Macica,CM;Yang,Y;Hebert,SC;Wang,WH
花生四烯酸（AA）已被证明能抑制皮质集合管顶膜低电导ATP敏感性K+通道的活性[W. Wang，中国山核桃A.卡索拉和G.吉比施Am. J.Physiol.262（Renal Fluid Electrolyte Physiol.31）：F554-F559，1992]。ROMK 1是一种来源于大鼠肾脏外髓质的K+通道，具有许多天然低电导K+通道的生物物理特性，其定位于皮质集合管和粗升支的顶膜。本研究旨在确定ROMK通道是否保持天然低电导K+通道的AA敏感性。实验在非洲爪蟾卵母细胞中进行，通过使用膜片钳技术注射编码ROMK 1通道的cRNA。我们已经证实了以前的报道，克隆的ROMK 1具有类似的通道动力学，高开放概率，和内向斜率电导作为天然低电导K+通道，分别。将5 μ M AA添加到由内而外的贴片中，导致在与AA对天然K+通道的抑制剂常数相似的浓度下可逆地抑制通道活性。AA对通道活性的影响在10 μ M吲哚美辛（一种环氧合酶抑制剂）、4 μ M肉桂基-3，4-二羟基氰基肉桂酸酯（一种脂氧合酶抑制剂）和4 μ M 17-十八炔酸（一种细胞色素P-450单加氧酶抑制剂）的存在下得以保留，因此表明AA的作用不由AA的代谢产物介导。这种效应似乎不是膜流动性变化的结果，因为5 μ M二十碳四炔酸（一种AA类似物，是膜流动性的有效调节剂）没有影响。此外，添加AA的补丁外也没有影响通道的活动。这些结果表明，与天然低电导通道一样，AA能够直接抑制ROMK 1通道活性。
Arachidonic acid (AA) has been shown to inhibit the activity of the low-conductance ATP-sensitive K+ channel in the apical membrane of the cortical collecting duct [W. Wang, A. Cassola, and G. Giebisch. Am. J. Physiol. 262 (Renal Fluid Electrolyte Physiol. 31): F554-F559, 1992]. ROMK1, a K+ channel derived from the rat renal outer medulla, shares many biophysical properties of the native low-conductance K+ channel, which is localized to the apical membranes of the cortical collecting duct and thick ascending limb. This study was designed to determine whether the ROMK channel maintains the property of AA sensitivity of the native low-conductance K+ channel. Experiments were conducted in Xenopus oocytes injected with cRNA encoding the ROMK1 channel by use of patch-clamp techniques. We have confirmed previous reports that the cloned ROMK1 has similar channel kinetics, high open probability, and inward slope conductance as the native low-conductance K+ channel, respectively. Addition of 5 microM AA to an inside-out patch resulted in reversible inhibition of channel activity at a concentration similar to the inhibitor constant for AA on the native K+ channel. The effect of AA on channel activity was preserved in the presence of 10 microM indomethacin, a cyclooxygenase inhibitor, 4 microM cinnamyl-3,4-dihydroxycyanocinnamate, a lipoxygenase inhibitor, and 4 microM 17-octadecynoic acid, an inhibitor of cytochrome P-450 monooxygenases, thus indicating that the effect of AA was not mediated by metabolites of AA. The effect did not appear to be the result of changes in membrane fluidity, since 5 microM eicosatetraynoic acid, an AA analogue that is a potent modulator of membrane fluidity, had no effect. Furthermore, the addition of AA to the outside of the patch also had no effect on channel activity. These results indicate that, like the native low-conductance channel, AA is able to directly inhibit ROMK1 channel activity.