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本研究应用全细胞膜片钳技术在离体豚鼠小脑前下动脉(AICA)和肠系膜动脉(MA)的平滑肌细胞上,观察300μmol/L 18β-甘草次酸(18βGA)对微动脉平滑肌细胞膜电流的影响。结果显示:(1)18βGA能够增强微动脉平滑肌细胞外向电流,300μmol/L 18βGA使AICA和MA平滑肌细胞外向电流(+40mV)分别从234±36pA和154±25pA增强到376±41pA(n=8,P<0.05)和348±45pA(n=11,P<0.01)。18βGA增强微动脉平滑肌细胞外向电流具有电压依赖性,18βGA主要增强0～+40mV电压区间的激活电流,其中对+40mV阶跃电压激活电流的作用最强。(2)300μmol/L 18βGA的净电流与10mmol/L TEA和50nmol/L ChTX相似,与1mmol/L 4-AP不同。预灌流10mmol/L TEA后300μmol/L 18βGA对微动脉平滑肌细胞外向电流的增强作用完全消失。上述结果提示300μmol/L 18βGA能够电压依赖的增强豚鼠AICA和MA微动脉平滑肌细胞BKCa通道电流。
In this study, the effect of 300μmol / L 18β-glycyrrhetinic acid (18βGA) on the membrane currents of arterial smooth muscle cells was observed using whole-cell patch clamp technique on smooth muscle cells of guinea pig anterior inferior cerebellar artery (AICA) and mesenteric artery (MA) . The results showed that: (1) 18βGA enhanced the outward currents of VSMCs, 300μmol / L 18βGA enhanced the outward current (+ 40mV) of AICA and MA smooth muscle cells from 234 ± 36pA and 154 ± 25pA to 376 ± 41pA (n = 8 , P <0.05) and 348 ± 45 pA (n = 11, P <0.01). 18βGA enhances the outward current of VSMCs in a voltage-dependent manner. 18βGA mainly enhances the activation current in the voltage range of 0 ~ + 40mV, and the strongest effect on the +40 mV step voltage-activated current. (2) The net current of 300μmol / L 18βGA was similar to that of 10mmol / L TEA and 50nmol / L ChTX, which was different from that of 1mmol / L 4-AP. After pre-perfusion of 10 mmol / L TEA, 300 μmol / L 18βGA completely abolished the enhancement of outward current of smooth muscle cells. The above results suggest that 300μmol / L 18βGA can increase voltage-dependently the currents of BKCa channels in guinea pig AICA and MA arterial smooth muscle cells.