乙氧异黄酮二酸钠对豚鼠单个心室肌细胞钙电流的影响

Effects of Ethoxy-Isoflavone 2-Carboxycic Acid on Ca￣(2+) Current of Ventricular Myocytes in Guinea Pigs

应用全细胞膜片钳技术，研究乙氧异黄酮二酸钠（ｅｔｈｏｘｙ－ｉｓｏｆｌａｖｏｎｅ２－ｃａｒｂｏｘｙｌｉｃａｃｉｄ，ＥＩＣＡ）对豚鼠心室肌细胞上慢钙电流（Ｉｃａ）的影响。结果发现ＥＩＣＡ能使心室肌细胞Ｉｃａ呈剂量依赖性降低，阈浓度为１０－８ｍｏｌ／Ｌ，最大有效浓度为３×１０－５ｍｏｌ／Ｌ；１０－６ｍｏｌ／ＬＥＩＣＡ可明显阻断异丙肾上腺素（Ｉｓｏｐｒｅｎａｌｉｎｅ，Ｉｓｏ）和钙通道激动剂ＢａｙＫ８６４４所致的Ｉｃａ增加（Ｐ＜０．０１）。ＥＩＣＡ能增加外向电流（Ｌｏｕｔ），并被四乙基胺（Ｔｅｔｒａｅｔｈｙｌａｍｍｏｎｉｕｍ，ＴＥＡ，１０－６ｍｏｌ／Ｌ）所拮抗。结果提示：ＥＩＣＡ的降压、减慢心率、抗心律失常作用机制主要与阻断Ｃａ２＋通道（Ｌ型）有关。

The efffects of Fthoxy-Isoflavone 2-Carboxylic acid(EICA) on the slow Ca2+ currents(Ica) in a single cell of ventricular myocyte in guinea pig were studied using the whole cell recording patch clamp technique.Results showed that this Ica was decreased by EICA(from 10-8mol/L to 10-5 mol/L) in a dose-dependent manner.However,effects of Iso or Bay K8644 -induced increase of Ica may be markedly affected by 10-6mol/L EICA[from(1.22±0.19) nA to(0.57±0.13) nA or from(1.23±0.16) nA to(0.53±0.17) nA].In addition,it was observed that 10-6 mol/L EICA markedly increased the amplitude of outward current Iout,while tetraethylammonium(TEA) exerted a significant antagonistic action.The results demonstrated that EICA can depress the transomembrane calcium current and may also enhance the K+ outward current in the ventricular myocytes.