【摘要】 本文旨在探讨大鼠新鲜离体输精管平滑肌细胞中乙酰胆碱(acetylcholine, ACh)引起超极化反应的机制,采用细胞内微电极记录技术和细胞内荧光标记技术研究 ACh 对大鼠输精管不同走行方向平滑肌细胞的作用。用尖端含 0.1% 碘化吡啶(propidium iodide, PI)的记录电极标记电生理记录后的平滑肌细胞,其中 37 个为外层纵行细胞,17 个为内层环行细胞。它们的平均静息膜电位分别为(–53.56±3.88) mV 和 (–51.62±4.27) mV,膜输入阻抗分别为(2 245.60±372.50) MΩ和 (2 101.50±513.50)MΩ。ACh 引起的膜超极化反应是浓度依赖性的, EC50 为 36 μmol/L。ACh 引起的超极化反应可被非选择性的毒蕈碱(muscarinic receptor, M) 受体阻断剂阿托品(atropine, 1 μmol/L)和选择性的 M3 受体阻断剂 diphenylacetoxy-N-methylpiperidine-methiodide (DAMP, 100 nmol/L)阻断。ACh 引起的超极化还能被一氧化氮合酶抑制剂L-硝基-精氨酸甲酯(N-nitro-L-arginine methylester, L-NAME, 300 μmol/L)阻断,并可被 ATP 敏感的钾通道阻断剂 glipizide (5 μmol/L) 或内向整流钾通道阻断剂钡离子(50μmol/L)部分阻断。Glipizide 和钡离子联合使用可完全阻断 ACh 引起的超极化反应。上述结果表明:ACh 通过作用于大鼠输精管平滑肌细胞膜上的M3 受体引起超极化反应,一氧化氮、ATP 敏感性钾通道和内向整流钾通道参与了ACh 引起的超极化反应 。更多还原

【Abstract】 To explore the underlying mechanism of acetylcholine (ACh)-evoked membrane hyperpolarizing response in isolated rat vas deferens smooth muscle cells (SMCs), intracellular microelectrode recording technique and intracellular microelectrophoresis fluorescent staining technique were used to study ACh-evoked membrane hyperpolarizing response in SMCs freshly isolated from Wistar rat vas deferens. By using microelectrodes containing fluorescent dye 0.1% propidium iodide (PI), 37 and 17 cells were identified as SMCs in outer longitudinal and inner circular muscular layers, respectively. The resting membrane potentials of SMCs were (–53.56±3.88) mV and (–51.62±4.27) mV, respectively. The membrane input resistances were (2 245.60±372.50) MΩ and (2 101.50±513.50) MΩ, respectively. ACh evoked membrane hyperpolarizing response in a concentration-dependent manner with an EC50 of 36 μmol/L. This action of ACh was abolished by both a non-sepcific muscarinic (M) receptor antagonist atropine (1 μmol/L) and a selective M3 receptor antagonist diphenylacetoxy-N-methylpiperidine-methiodide (DAMP, 100 nmol/L). ACh-evoked mem- brane hyperpolarization was also abolished by a nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME, 300 μmol/ L) and suppressed by an ATP-sensitive potassium (KATP) channel blocker glipizide (5 μmol/L) and an inward rectifier potassium (Kir) channel inhibitor bariumion (50 μmol/L). A combination of glipizide and bariumion abolished ACh-evoked membrane hyperpolarizing response. The results suggest that ACh-evoked membrane hyperpolarization in rat vas deferens SMCs is mediated by M3 receptor followed with activation of KATP channels, Kir channels, and NO release.更多还原