小鼠小肠迷走神经初级传入神经元酸敏感电流的特征

目的 分析小鼠小肠迷走神经初级传入神经元上酸敏感电流的特征及药理学特性,初步探讨介导酸敏感电流的离子通道.方法 运用活性荧光染料（DiI）逆行标记小鼠小肠迷走神经初级传入神经元,全细胞膜片钳技术记录和分析不同pH值的细胞外液刺激诱发的酸敏感电流及与pH值的关系.在pH值5.0的细胞外液中（对照）分别添加酸敏感离子通道（ASIC）拮抗剂（30 μmol/L benzamil和100 μmol/L amiloride）和瞬时受体电位香草酸亚型1（TRPV1）拮抗剂（10 μmol/L capsazepine和10 μmol/L ruthenium red）,观察诱发酸敏感电流的变化.结果 在DiI标记的52个神经元中的33个神经元上可记录到三种类型的内向电流（快、慢和持续型）.酸敏感电流的电流幅度均随pH值的降低而增大.30 μmol/L benzamil和100 μmol/L amiloride使快电流的瞬时成分和慢电流的电流幅度显著减小（P＜0.05和P＜0.01）;10 μmol/L capsazepine和10 μmol/L ruthenium red能使持续型电流的电流幅度明显减小（均P＜0.05）.结论 小肠迷走神经初级传入神经元至少表达三种对酸反应的离子通道,分别是ASIC的两种不同亚型和TRPV1.

Properties of acid-sensing currents in vagal primary afferent neurons of murine small intestine

Objective To investigate the electrophysiological and pharmacological properties of acid-sensing currents in vagal primary afferent neurons innervating murine small intestine, and explore the ion channels inducing acid-sensing currents. Methods Vagal primary afferent neurons were labeled retrogradely through injection of active fluorescent dye (DiI) into the jejunal wall, whole-cell patch clamp technique was employed to record the acid-sensing currents induced by extracellular fluid with different pH, and the relationship between acid-sensing currents and pH was explored. Acid-sensing ion channel (ASIC) antagonists (30 μmol/L benzamil and 100 μmol/L amiloride) and transient receptor potential vanilloid-1 (TRPV1) antagonists (10 μmol/L capsazepine and 10 μmol/L ruthenium red) were added to extracellular fluid with pH 5 (control), and the changes of induced acid-sensing currents were observed. Results Among a total of 52 DiI-labled neurons, inward currents consisting of three distinct types (fast-type current, slow-type current and sustained current) were recorded in 33 neurons. The amplitudes of acid-sensing currents increased with the decrease of pH. The transient component of fast-type current and amplitude of slow-type current significantly decreased by 30 μmol/L benzamil and 100 μmol/L amiloride (P<0.05 and P<0.01), and the amplitude of sustained current significantly decreased by 10 μmol/L capsazepine and 10 μmol/L ruthenium red (P<0.05). Conclusion Vagal primary afferent neurons of the small intestine express at least three types of acid-responsive ion channels, including TRPV1 and two subtypes of ASIC.