K^+通道在正常与慢性低氧大鼠低氧性肺血管收缩反应中的作用

Role of K^+ channels in hypoxic pulmonary vasoconstriction in normal and chronic hypoxic rats

目的 :探讨K+ 通道在慢性低氧致低氧性肺血管收缩反应降低中的作用。方法 :采用离体肺灌流实验 ,研究 4-AP(4-aminopyridine ,电压依赖性K+ 通道 -Kv阻滞剂 )、TEA(tetraethylamonium ,Ca2 + 激活性K+ 通道 -KCa阻滞剂 )、GLIB(glibenclamide,ATP敏感性K+ 通道 -KATP阻滞剂 )对正常与慢性低氧大鼠肺血管低氧反应的影响。结果 :4-AP、TEA均可使正常大鼠肺动脉基础压上升 ,且使其肺血管低氧反应明显增强 ;对于慢性低氧大鼠 ,其肺血管对低氧反应明显低下 ,4-AP、TEA升肺动脉基础压的作用明显低于对照鼠肺 ,GLIB也呈现升高肺动脉基础压力作用 ,4-AP、TEA、GLIB均可使肺血管低氧反应大大增强 ,增强的比例明显大于正常对照组。结论 :在离体灌流鼠肺HPV中 ,Kv、KCa的开放起调节作用 ,大鼠经慢性低氧后 ,肺血管反应性明显降低 ,可能与Kv、KCa。

AIM: To investigate the role of K + channels in the decreased hypoxic pulmonary vasoconstriction(HPV) in chronic hypoxic rats. METHODS: Blockers of three kinds of K + channels, 4-AP(voltage dependent K + channel blocker), TEA(Ca 2+ activated K + channel blocker)\, GLIB(ATP sensitive K + channel blocker) were used in isolated perfused rat lungs to detect the role of K + channels in HPV. RESULTS: In normal rats, 4-AP and TEA, but not GLIB, both elicited a significant increase in pulmonary artery baseline pressure, and also potentiated the acute hypoxic pulmonary vasoconstriction. In chronic hypoxic rats, the HPV is significantly decreased, while 4-AP, TEA, GLIB all elicited a significant but smaller increase in pulmonary artery baseline pressure. Additionally, all these three blockers potentiated the HPV stronger in chronic hypoxic rats than in control rats. CONCLUSION: The opening of Kv, K Ca , K ATP might modulate the hypoxic pulmonary vasoconstriction in isolated rat lungs, and the increase in this modulation by potassium channel in chronic hypoxic rats might play a role in its decrease in HPV.