摘要
目的研究KCNE2对人类心肌细胞瞬间外向钾电流的主要α亚基-Kv4.3功能的调节。方法通过基因转染技术将Kv4.3或Kv4.3与KCNE2cDNA转入COS-7细胞株,采用膜片钳全细胞记录方式记录通道电流。结果KCNE2对Kv4.3功能有明显调控作用:减小Kv4.3通道电流密度;Kv4.3单独表达组通道电流密度为375.13±112.87pA/pF(n=11),KCNE2与Kv4.3共表达组电流密度为152.96±33.71pA/pF(n=16);减慢Kv4.3通道激活和衰减,在+60mV电压刺激下通道激活达峰值的时间由4.82±0.32ms(n=11)延长至20.41±2.13ms(n=16),P<0.05;通道电压依赖性失活发生正向移位,半数失活电压由-53.62±1.24mV(n=8)移至-46.58±1.6mV(n=10);通道从失活中恢复的速度加快,恢复时间常数由193.43±17.98ms缩短137.71±18.29ms,(n=7,P<0.05)。结论KCNE2可能作为人类心肌细胞膜Kv4.3钾离子通道一个重要的辅助亚基-β亚基参与Ito通道功能的调节。
Objective To understand the role of KCNE2 in functional regulation of Kv4.3, the major α subunit of transient outward current (Ito) in human heart. Methods The cDNAs of Kv4.3 or Kv4.3 plus KCNE2 were transfected into COS-7 cells and 24-36 h after the transfection, the channel proteins were expressed in the surface membrane of the cells and the channel currents were recorded with patch-clamp technique in whole-cell mode. Results KCNE2 played an important role in modulating the channel function. The recorded current density was decreased in cells co-expressing KCNE2 and Kv4.3 to 152.96±33.71 pA/pF (n=16) as compared with Kv4.3-expressing cells with a mean current density of375.13±112,87 pA/pF (n=11). At the recording voltage of 60 mV, KCNE2 increased the time to peak (TTP) of the current. TTP in only Kv4. 3-expressing cells was 4.82±0.32 ms (n= 11), significantly shorter than the TTP of 20.41 ±2.13 ms (n=16) in cells co-expressing Kv4.3 and KCNE2 (P〈0.05). In the presence of KCNE2, the voltage-dependent inactivation of Kv4,3 showed a positive shift. The voltage of half maximum inactivation (V0s) was decreased significantly from -53.62±1.24 mV (n=8) in Kv4.3 group to -46.58±1.6 mV (n=10) in KCNE2 co-expression group (P〈0.05). KCNE2 accelerated the recovery of the channel from inactivation, reducing the recovery time constant (r) from 193.43±17.98 ms to 137.71 ±18.29 ms. Conclusion KCNE2 might serve as an important 13 subunit and play a role in the regulation of Ito function in human heart.
出处
《南方医科大学学报》
CAS
CSCD
北大核心
2006年第12期1754-1756,共3页
Journal of Southern Medical University
基金
国家自然科学基金(30570418
30570940)~~