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目的 观察5 - 羟色胺(5 - HT)对豚鼠结肠平滑肌细胞膜离子通道电流和膜电位的电生理作用。方法 用EPC 9膜片钳和图像分析软件系统检测5 - HT对细胞收缩、动作电位(AP)、静息电位(RP)、钙依赖钾通道(BKCa)、钙通道(Ca2 + L)电流的影响。结果 10 μmol/L 5 - HT对平滑肌细胞的直接作用:①外源性刺激的AP峰值下降至6 0 %±7.3% (n =7,P <0 .0 0 1) ,快速复极时间由4 7.5 3ms±4 .88ms下降为2 2 .96ms±4 .6 5ms(n =7,P <0 .0 0 1)。②RP从- 6 8.4mV±- 3.6mV(n =11)下降为- 18.2mV±- 2 .5mV(n =7,P <0 .0 0 1)。③从- 6 0mV去极化至+6 0mV时的细胞BKCa升高2 7%±12 % (n =8,P <0 .0 1) ,而电极内液含10 μmol/L肝素时则没有影响(2 .2 %±3.1% ,n =5 ,P >0 .0 5 )。④从- 6 0mV去极化至0mV的钙电流增加(2 3%±7% ,n =7,P <0 .0 1) ,而电极内液含10μmol/L肝素时则没有影响(2 .5 %±3.1% ,n =7,P >0 .0 5 ) ,细胞外液加入5 μmol/L尼卡地平(Nicardip ine)仍能抑制钙电流(79.3%±5 .1% ,n =3,P <0 .0 1)。结论 5 - HT主要通过IP3途径作用于豚鼠结肠平滑肌细胞:①可增加钙电流和使细胞去极化引起平滑肌细胞收缩。②使静息电位下降和细胞内外的游离钙离子浓度差减小,从而降低AP幅值。③兴奋BKCa电流促进AP
Aim To observe the electrophysiological effects of 5 - hydroxytryptamine (5 - HT) on membrane ion channel current and membrane potential in guinea pig colonic smooth muscle cells. Methods EPC 9 patch clamp and image analysis software were used to detect the effects of 5 - HT on the cell contraction, action potential (AP), resting potential (RP), calcium dependent potassium channel (BKCa), calcium channel (Ca2 + influences. Results The direct effects of 10 μmol / L 5 - HT on smooth muscle cells were as follows: ① The peak of exogenous AP decreased to 60% ± 7.3% (n = 7, P <0.01) 4 7.5 3ms ± 4 .88ms decreased to 2 2 .96ms ± 4. 65ms (n = 7, P <0. 001). ② The RP decreased from -6.4mV ± - 3.6mV (n = 11) to -18.2mV ± -2.5mV (n = 7, P <0.001). ③ BKCa increased 27.7% ± 12% (n = 8, P <0.01) when depolarized from -600 mV to +6 0 mV, while there was no increase in the electrode solution containing 10 μmol / L heparin Effect (2.2% ± 3.1%, n = 5, P> 0.05). ④ Calcium current depolarized to 0mV from -60mV increased (23% ± 7%, n = 7, P <0.01), while there was no effect in the electrode solution containing 10μmol / L heparin (2. 5% ± 3.1%, n = 7, P> 0.05). The addition of 5 μmol / L nicardipine could inhibit the calcium current (79.3% ± 5.1%, n = 3 , P <0. 01). Conclusion 5 - HT acts on the smooth muscle cells of guinea pig colon mainly through the IP3 pathway: ① It can increase the calcium current and depolarize the cells to cause the contraction of smooth muscle cells. ② so that the resting potential and intracellular free calcium ion concentration difference decreases, thereby reducing the AP amplitude. ③ excited BKCa current to promote AP