Cardiovascular and Renal Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark.
Basic Clin Pharmacol Toxicol. 2013 Oct;113(4):250-8. doi: 10.1111/bcpt.12092. Epub 2013 Jun 27.
Polyunsaturated fatty acid (PUFA)-activated two-pore domain potassium channels (K2P ) have been proposed to be expressed in the pulmonary vasculature. However, their physiological or pathophysiological roles are poorly defined. Here, we tested the hypothesis that PUFA-activated K2P are involved in pulmonary vasorelaxation and that alterations of channel expression are pathophysiologically linked to pulmonary hypertension. Expression of PUFA-activated K2P in the murine lung was investigated by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), by patch clamp (PC) and myography. K2P -gene expression was examined in chronic hypoxic mice. qRT-PCR showed that the K2P 2.1 and K2P 6.1 were the predominantly expressed K2P in the murine lung. IHC revealed protein expression of K2P 2.1 and K2P 6.1 in the endothelium of pulmonary arteries and of K2P 6.1 in bronchial epithelium. PC showed pimozide-sensitive K2P -like K(+) -current activated by docosahexaenoic acid (DHA) in freshly isolated endothelial cells as well as DHA-induced membrane hyperpolarization. Myography on pulmonary arteries showed that DHA induced concentration-dependent instantaneous relaxations that were resistant to endothelial removal and inhibition of NO and prostacyclin synthesis and to a cocktail of blockers of calcium-activated K(+) channels but were abolished by high extracellular (30 mM) K(+) -concentration. Gene expression and protein of K2P 2.1 were not altered in chronic hypoxic mice, while K2P 6.1 was up-regulated by fourfold. In conclusion, the PUFA-activated K2P 2.1 and K2P 6.1 are expressed in murine lung and functional K2P -like channels contribute to endothelium hyperpolarization and pulmonary artery relaxation. The increased K2P 6.1-gene expression may represent a novel counter-regulatory mechanism in pulmonary hypertension and suggest that arterial K2P 2.1 and K2P 6.1 could be novel therapeutic targets.
多不饱和脂肪酸（PUFA）激活的双孔钾通道（K2P）被认为在肺血管中表达。然而，其生理或病理生理作用尚未明确。在这里，我们测试了以下假设：PUFA 激活的 K2P 参与肺血管舒张，并且通道表达的改变与肺动脉高压在病理生理学上相关。通过定量逆转录聚合酶链反应（qRT-PCR）、免疫组织化学（IHC）、膜片钳（PC）和肌动描记术检测了 K2P 在小鼠肺部的表达。在慢性缺氧小鼠中检查了 K2P 基因表达。qRT-PCR 显示 K2P 2.1 和 K2P 6.1 是小鼠肺部表达最丰富的 K2P。IHC 显示 K2P 2.1 和 K2P 6.1 的蛋白表达在肺小动脉内皮中，以及 K2P 6.1 在支气管上皮细胞中。PC 显示在新鲜分离的内皮细胞中，普瑞巴林敏感的 K2P 样 K(+) 电流由二十二碳六烯酸（DHA）激活，以及 DHA 诱导的膜超极化。肺血管肌动描记术显示，DHA 诱导浓度依赖性的瞬间松弛，这种松弛对内皮去除和一氧化氮和前列环素合成的抑制以及钙激活的 K(+) 通道阻断剂鸡尾酒均有抗性，但在外腔（30 mM）高 K(+) 浓度下被消除。慢性缺氧小鼠中 K2P 2.1 的基因表达和蛋白均未改变，而 K2P 6.1 的表达上调了四倍。总之，PUFA 激活的 K2P 2.1 和 K2P 6.1 在小鼠肺中表达，功能性 K2P 样通道有助于内皮超极化和肺血管舒张。K2P 6.1 基因表达的增加可能代表肺动脉高压的一种新的代偿调节机制，并表明动脉 K2P 2.1 和 K2P 6.1 可能成为新的治疗靶点。
