哮喘豚鼠气管平滑肌钾离子通道特性的改变

Changes of K + channel behaviors in airway smooth muscle from asthmatic guinea pigs

目的为探讨哮喘时电压依赖性钾离子通道（ⅠＫ）特性的改变。方法在支气管平滑肌细胞膜上，用膜片钳技术进行了研究。结果哮喘平滑肌细胞有如下改变：（１）静息跨膜电位差值降低。（２）通道电导值与正常组相比下降了约５１％。（３）开放时间常数的快、慢成分明显缩短，分别下降到正常对照组的２５％和７％。关闭时间常数明显延长。（４）开放概率有电压依赖性，但在相同的钳制电压范围内明显降低。结论哮喘气道高反应性时钾离子通道动力学活性明显衰减，提示将导致细胞兴奋阈降低。

Objective To observe asthma induced changes of single K + channel behaviors in acutely dissociated airway smooth muscle of guinea pig. Methods The resting membrane potential (MP) was measured in whole cell recording configuration. The elementary currents flowing through single K + channel were recorded in cell attached patches. Results The properties in asthmatic group were as follows: (1) MP was decreased from -70.3±3.5mV to -62.8±5.6mV. (2) In the same depolarization conditions, the amplitudes of currents decayed and conductant values were decreased with significantly difference (about 51%) from the values obtained from the control group. (3) Open time constants of fast and slow open states shortened markedly to 25% and 7% of controls respectively. Shut time constants were prolonged. (4) Open probability showed voltage dependence and was decreased in the same voltage range. Conclusions Asthmic airway hyperreactivity related kinetic properties of K + channel deficits, which may result a reduced threshold of excitation.