甲状腺素诱导的豚鼠肥厚心肌中延迟整流钾电流离子通道特征

Characteristics of the delayed rectifier K^+ current in guinea pig hypertrophied ventricular myocytes induced by thyroxine

目的在甲状腺素诱导的豚鼠心肌肥厚模型上，研究肥厚心肌细胞延迟整流钾电流（ＩＫ）中快激活成份（Ｉｋｒ）及慢激活成份（Ｉｋｓ）离子通道特征。方法采用全细胞膜片钳技术。结果在甲状腺素诱导的肥厚心肌细胞中，Ｉｋｒ及Ｉｋｓ的电流幅度随去极化电压的增加较正常心肌细胞明显增大，且Ｉｋｒ ｔａｉｌ及Ｉｋｓ的增加程度分别大于Ｉｋｒ及Ｉｋｓｔａｉｌ°心肌肥厚使Ｉｋｓ激活曲线向负的电压方向偏移，对Ｉｋｒ激活曲线无明显影响。结论甲状腺素诱导的肥厚心肌使Ｉｋｒ及Ｉｋｓ明显增加。

AIM To study the characteristic of the rapidly activating component (Ikr) and the slowly activating component (Iks) of the delayed rectifier K+ current in guinea pig hypertrophied ventricular myocytes induced by thyroxine. METHOD The whole cell patch clamp techniques were used. RESULTS In hypertrophied ventricular myocytes, the magnitude of in and im were greatly augmented with more positive depolarizations, and the degree of increase of Ikr, tail and Iks were greater than that of Ikr and Iks tail, respectively. By measuring the amplitude of tall currents which reflected the degree of activation, the activation curve of Iks was shifted toward more negative potential, but that of Ikr was markedly unaffected in hypertrophied myocytes. CONCLUSION Hypertrophied ventricular myocytes induced by thyroxine obviously increased Ikr and Iks.