15-HETE对缺氧兔肺动脉平滑肌钾离子通道的影响

用肺动脉环和全细胞膜片钳技术研究15-羟化二十烷四烯酸(15-HETE)对缺氧兔肺动脉平滑肌钾离子通道的影响。新出生的幼兔分两组,一组放入吸氧分数为0．12的低氧舱内;另一组保持正常氧环境。9d后,称重、取肺动脉进行细胞培养并制作肺动脉环。分别加入4-氨基吡啶(4-aminopyridione,4-AP)、四乙胺(tetraethylammonium,TEA)、glyburide(GLYB)三种特异性钾离子通道阻断剂,观察15-HETE对兔肺动脉平滑肌钾离子通道的作用变化,同时采用全细胞膜片钳测定钾电流。结果显示：5mmol／L 4-AP阻断Kv通道后可以抑制15-HETE诱导的缺氧兔肺动脉收缩;TEA和GLYB分别阻断大电导型钙激活钾通道(BKCa)和KATP通道后并不影响15-HETE诱导的缺氧兔肺动脉收缩;15-HETE可降低兔肺动脉平滑肌细胞钾电流幅度。上述结果提示：缺氧兔肺动脉中,15-HETE阻断电压依赖钾通道(Kv通道),引起膜去极化,可能是缺氧性肺血管收缩的机制之一。

Effect of 15-HETE on potassium channels of rabbit pulmonary arterial smooth muscles during hypoxia

This study investigated the role of 15-hydroxyeicosatetraenoic acid (15-HETE) in rabbit pulmonary arterial smooth muscle cells (PASMCs) under hypoxia by using organ bath and whole cell patch-clamp techniques. Neonatal rabbits born into normoxic environment were transferred after first feeding into normal and hypoxic environments with respectively 0.21 and 0.12 fractional inspired oxygen (FiO2). Pulmonary arteries were extracted after 9 d and cut into rings 1.0 approximately 1.5 mm in length for organ bath experiments. Whole cell patch-clamp technique was used to measure the potassium current in the freshly dispersed rabbit PASMCs. The results showed that 15-HETE-induced vasoconstriction was blocked by 4-aminopyridine (5 mmol/L), a Kv channel blocker. The K(ATP) channel blocker glyburide (1 micromol/L) and the BKCa channel blocker tetraethylammonium (10 mmol/L) did not abolish this vasoconstriction. 15-HETE decreased the whole-cell voltage-gated K+ current in the PASMCs. These findings demonstrate that hypoxia blocks Kv channels through a 15-HETE mediated mechanism, leading to PA vasoconstriction.