Kv在正常与被动致敏人气道平滑肌张力调控中的作用

Regulatory effects of Kv on the tension of normal and passively sensitized human airway smooth muscle

目的:探讨电压依赖性延迟整流钾通道(Kv)对正常与体外致敏人气道平滑肌(HASM)的张力调控作用及其机制。方法:采用肌张力试验、逆转录聚合酶链反应(RT-PCR)和免疫细胞化学等技术,观察钾通道阻断剂对正常与哮喘患者血清致敏HASM张力、细胞Kv的mRNA和蛋白质表达。结果:Kv阻断剂4-氨基吡啶(4-AP)可引起正常HASM肌环产生浓度依赖性收缩反应,达到最大效应一半所需浓度的负对数值(pD2)为2.09±0.09,人哮喘血清致敏组为2.44±0.16,差异显著(P<0.01);但最大反应强度(Emax)分别为正常组(24.0±6.4)g/g,人哮喘血清致敏组(31.8±7.3)g/g,差异无显著(P>0.05)。在培养的HASM细胞上,Kv1.2、Kv1.3和Kv1.5基因mRNA均有表达;人哮喘血清致敏的HASM细胞Kv1.5基因mRNA(P<0.01)和蛋白质(P<0.01)的表达均下降。结论:体外被动致敏HASM细胞Kv功能较正常下调,致平滑肌兴奋性增高,该变化可能主要与Kv1.5基因相关。

AIM： To investigate the regulatory effects of voltage- dependent delayed rectifier potassium channel （Kv） on the tension of normal and passively sensitized human airway smooth muscle （ HASM）. METHODS： By using blockers of potassium channels as tools, the tension of HASM and Kv gene mRNA and protein expressions in normal and asthmatics serum sensitized HASM cells were measured with techniques of reverse transcriptase/polymerase chain reaction （RT- PCR） and immunocyto- chemistry. RESULTS： （ 1 ） 4 - aminopyridine （4 - AP）, the blocker of Kv, caused a concentration dependent constriction in normal HASM rings. The negative logarithm of the drug concentration causing 50% of maximal effect （pD2） in normal group （2.09 ± 0.09） was significantly different from that in the sensitized group （2.44±0.16, P〈0.01）. The maximal effect （Emax） of normal group [ （24.0 ± 6.4）g/g] had no significant difference from that of the asthmatics serum sensitized group [ （31.8 ± 7.3）g/g] （ P 〉 0.05）. （2） There were Kv1. 2, Kv1. 3 and Kv1. 5 mRNA expressions in cultured HASM cells, but only Kvl. 5 mRNA （P 〈 0.01 ） and protein （ P 〈0.01） expressions were reduced in HASM cells sensitized with serum from asthmatic patients. CONCLUSION： The function of Kv is decreased in passively sensitized HASM cells, which causes the increasing excitability of HASM celLs. This change may be mainly related to Kv1.5.