白花前胡甲素对豚鼠单一心室肌细胞Ⅰ_K通道作用机制的初步探讨

The preliminary research of dl-prearuptorin A in mechanism of action on delayed outward potassium current

目的通过比较白花前胡甲素（Pd－Ia）与异丙肾上腺素对豚鼠单一心室肌细胞迟发性外向钾电流（IK）的影响，初步探讨Pd－Ia开放钾通道作用的可能机制。方法；应用全细胞膜片钳制技术。结果与结论：Pd－Ia对IK通道作用的最大效应与异丙肾上腺素相近，均使IK增加2～2．5倍，对IK的激活动力学过程均无明显影响，而且两药的作用不具有相加性。另外，乙酰胆碱对Pd－Ia增加IK作用的影响也与对异丙肾上腺素的影响相似，提示Pd－Ia对IK的作用可能是通过激活PKA而产生的。其确切机制还有待进一步实验研究。

Through comparing the effect of dl-prearuptorin A (Pd-la) with that ofisoprenaline (IPA) on delayed outward potassi-um current (Ik) in single ventricular cells ofguinea pigs, the mechanisms that Pd-la openedthe potassium channels were evaluated. METHODS: With patch clamp technique (whole-cellrecording ). RESULTS and CONCLUSIONS:The maximal effect of Pd-la was similar to IPA.Both drugs increased the values of IK by 2～2. 5fold, and did not affect the activated kinetics.and had no additive effects, respectively. In ad-dition, acetylcholine inhibited the increase of IKeither by Pd-la or by IPAe. All these suggestedthat the mechanisms that Pd-la increased the IKis activating PKA probably, but the precisemechanism remains to be elucidated.