Department of Health Science, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
J Pharmacol Sci. 2012;120(1):59-62. doi: 10.1254/jphs.12050sc. Epub 2012 Aug 23.
The effect of cibenzoline, a class I antiarrhythmic drug, on Na(+)/Ca(2+) exchange current (I(NCX)) was investigated using the patch-clamp method. Cibenzoline inhibited the bi-directional I(NCX) in a concentration-dependent manner. The IC(50) values of cibenzoline for the outward and inward components of I(NCX) were 77 and 84 μM, respectively, with Hill coefficients of 1. Intracellular application of trypsin via the pipette solution did not change the inhibitory effect of cibenzoline. The inhibitory effect of cibenzoline on I(NCX) at pH(o) 6.5 was smaller than those at pH(o) 7.4 and pH(o) 8.2. We conclude that cibenzoline inhibits I(NCX) in supra-therapeutic concentrations.
采用膜片钳技术研究了 I 类抗心律失常药物西苯唑啉对 Na(+)/Ca(2+)交换电流（I(NCX)）的影响。西苯唑啉呈浓度依赖性抑制双向 I(NCX)。西苯唑啉对 I(NCX)外向和内向成分的 IC(50)值分别为 77 和 84 μM，Hill 系数均为 1。细胞内通过吸管溶液应用胰蛋白酶不会改变西苯唑啉的抑制作用。在 pH(o) 6.5 时，西苯唑啉对 I(NCX)的抑制作用小于 pH(o) 7.4 和 pH(o) 8.2 时的抑制作用。我们得出结论，西苯唑啉在治疗超浓度下抑制 I(NCX)。
