18β-甘草次酸对豚鼠微动脉平滑肌细胞间缝隙连接的抑制作用

Inhibitory effect of 18β-glycyrrhetinic acid on gap junction of vascular smooth muscle cells in guinea pig

目的:探讨18-β-甘草次酸(18βGA)对微动脉平滑肌细胞间缝隙连接的影响,为寻求强效和可逆的缝隙连接阻断剂提供实验依据。方法:胶原酶A处理的豚鼠肠系膜动脉(MA)和小脑前下动脉(AICA)(直径<100μm)进一步去除结缔组织后,应用全细胞膜片钳技术观察应用18βGA后微动脉段上平滑肌细胞膜电容(Cinput)、膜电导(Ginput)和膜电阻(Rinput)的变化。结果:MA和AICA微动脉段上平滑肌细胞Cinput及Ginput为消化的单个平滑肌细胞的10～20倍。18βGA可以浓度依赖和可逆地降低微动脉段上平滑肌细胞的Ginput和增加Rinput。18βGA抑制MA和AICA微动脉平滑肌细胞Ginput的IC50值分别为3.5和2.3μmol.L-1,2种微动脉间比较差异无统计学意义(P>0.05)。当18βGA浓度≥30μmol.L-1时,MA和AICA微动脉段上平滑肌细胞的Cinput、Ginput或Rinput与相应消化的单个平滑肌细胞比较差异无统计学意义(P>0.05)。结论:18βGA能强效、可逆性地阻断微动脉平滑肌细胞间缝隙连接,当18βGA的浓度≥30μmol.L-1时作用最显著,对MA和AICA微动脉细胞间缝隙连接的抑制效果相似,提示MA和AICA微动脉细胞间缝隙连接具有同源性。

Objective To discuss the influence of 18β-glycyrrhetinic acid（18βGA） on gap junction of vascular smooth muscle cells（VSMC） and provide experimental basis for powerful and reversible gap junction inhibitors.Methods The preparations of mesenteric artery（MA） and anterior inferior cerebellar artery（AICA）（OD100 μm） in guinea pig were digested with collagenase A and its adventitial tissues were cleaned.Whole-cell patch clamp recordings were used to study the effect of 18βGA on membrane input capacitance（Cinput）,membrane input conductance（Ginput） or membrane input resistance（Rinput） of VSMCs embedded in arteriole segments.Results The Cinput and Ginput of the in situ cells were about 10-20 times that of the respective dispersed cell in MA and AICA.18βGA concentration-dependently and reversibly suppressed Ginput or increased Rinput,with IC50 of 3.5 and 2.3 μmol·L-1 in acutely isolated MA and AICA segments respectively.There was not significant difference between MA and AICA（P0.05）.After application of 18βGA（≥30 μmol·L-1）,the Cinput,Ginput and Rinput of the in situ cells were very close to the respective dispersed cell in MA and AICA（P0.05）.Conclusion 18βGA is a powerful and reversible gap junction blocker,achieving a maximal effect at ≥30 μmol·L-1.No significant difference is observed between MA and AICA for the gap junction blockade potency,suggesting a homogeneous property of the gap junctions between MA and AICA.