丙咪嗪对大鼠心室细胞瞬间外向钾电流的抑制作用

目的：研究丙咪嗪大鼠心室细胞瞬间外向钾电流（Ｉｗ）的抑制作用,方法：膜片箝全细胞记录法。结果：丙咪嗪对Ｉｔｏ有浓度依赖性抑制作用,ＩＣ５０为６．０μｍｏｌ．Ｌ＾－１并明显加速该电流的灭活里程,在不同的测试电位下,丙咪嗪对该电流的抑制百分率没有差别,丙咪嗪对Ｉｔｏ的稳态激活和灭活苗曲线的半数膜电位都无明显影响,对Ｉｔｏ灭活后的再复活时程有延长趋势,但不显（τｃｏｎｔｒｏｌ＝３７±１１ｍｓ,τｄｒｕ

Imipramine blocks the transient outward potassium current in rat ventricular myocytes.

AIM: To examine the effects of imipramine on transient outward potassium current (I(to) in rat ventricular myocytes. METHODS: The patch-clamp whole-cell recording techniques were used. RESULTS: Imipramine resulted in a concentration-dependent inhibition of I(to) with the IC50 of 6.0 mumol.L-1 and a concentration-dependent acceleration of I(to) inactivation. The blocking showed no difference at different testing membrane potentials. Imipramine produced slight effects (about 3 and 4 mV, respectively) on steady-state activation and inactivation curves of I(to), and tended to prolong the recovery of I(to) from inactivation (tau control = 37 +/- 11 ms; tau drug = 58 +/- 17 ms), but not significant (n = 4, P > 0.05). The inhibitory effect of imipramine on Ito was increased when the prepulses were prolonged progressively from 0 to 120 ms. (tau control = 22 +/- 8 ms; tau drug = 14 +/- 5 ms). CONCLUSIONS: Imipramine blocked Ito in concentration-dependent but voltage-independent manners, and with "open channel blocking" properties.