【摘要】 本研究比较了转染的Kv4.2钾电流与原代培养大鼠海马神经元上瞬间外向钾电流(IA)动力学特征。实验采用瞬时转染,细胞培养和全细胞膜片钳记录等方法。结果表明:转染的Kv4.2通道电流和海马神经元上IA均具有明显的A型电流特征。海马神经元IA的半数最大激活电位和斜率因子分别为-10.0±3.3 mV和13.9±2.6 mV;半数最大失活电位和斜率因子分别为-93.0±11.4 mV和-9.0±1.5 mV;失活后再激活恢复时间常数(T)为27.9±14.1 ms。Kv4.2的半数最大激活电位和斜率因子分别为-9.7±4.1 mV和15.8±5.7 mV;半数最大失活电位和斜率因子分别为-59.4±12.2 mV和8.0±3.1 mV;Kv4.2的灭活后再激活的恢复时间常数τ为172.8±10.0 ms。结果提示:Kv4.2通道电流可能是海马神经元上的IA电流的主要成分,但不是唯一成分。更多还原

【Abstract】 The present study was carried out to determine the functional properties of Kv4. 2 expressed in mammalian cells in comparison with native transient potassium outward current ( IA ) in the hippocampal neurons. Transient transfection, cell culture and whole cell voltage clamp techniques were used. The results showed that IA in cultured rat hippocampal neurons and Kv4. 2 expressed in HEK293 cells both displayed "A"-type current properties. The activation curves of IA and Kv4. 2 were better fitted by simple Boltzmann function with V1/2 - 10. 0 ±3. 3 mV, k 13. 9 ±2. 6 mV for IA and V1/2 -9. 7 ±4. 1 mV, k 15. 8±5. 7 mV for Kv4. 2, respectively. The steady-state inactivation curves of IA had a midpoint of -93.0 ±11. 4 mV and a slope of 9.0 ±1. 5 mV. The voltage-dependence of inactivation for Kv4. 2 exhibited midpoint and slope values of -59. 4 ±12. 2 mV and 8. 0±3. 1 mV, respectively. The time constants (τ) of recovery from inactivation of IA and Kv4. 2 were 27. 9± 14. 1 ms and 172. 8 ±10. 0 ms, respectively. These results suggest that Kv4. 2 is probably a major isoform contributing to IA in hippocampus neurons.更多还原