Characterization of myenteric sensory neurons in the mouse small intestine

We recorded from myenteric AH/Dogiel type II cells, demonstrated mechanosensitive responses, and characterized their basic properties. Recordings were obtained using the mouse longitudinal muscle myenteric plexus preparation with patch-clamp and sharp intracellular electrodes. The neurons had an action potential hump and a slow afterhyperpolarization (AHP) current. The slow AHP was carried by intermediate conductance Ca2+-dependent K+-channel currents sensitive to charybdotoxin and clotrimazole. All possessed a hyperpolarization-activated current that was blocked by extracellular cesium. They also expressed a TTX-resistant Na+ current with an onset near the resting potential. Pressing on the ganglion containing the patched neuron evoked depolarizing potentials in 17/18 cells. The potentials persisted after synaptic transmission was blocked. Volleys of presynaptic electrical stimuli evoked slow excitatory postsynaptic potentials (EPSPs) in 9/11 sensory neurons, but 0/29 cells received fast EPSP input. The slow EPSP was generated by removal of a voltage-insensitive K+ current. Patch-clamp recording with a KMeSO4-containing, but not a conventional KCl-rich, intracellular solution reproduced the single-spike slow AHPs and low input resistances seen with sharp intracellular recording. Cell-attached recording of intermediate conductance potassium channels supported the conclusion that the single-spike slow AHP is an intrinsic property of intestinal AH/sensory neurons. Unitary current recordings also suggested that the slow AHP current probably does not contribute significantly to the high resting background conductance seen in these cells. The characterization of mouse myenteric sensory neurons opens the way for the study of their roles in normal and pathological physiology.

我们对肌间神经丛的AH/多吉尔II型细胞进行了记录，展示了其机械敏感反应，并描述了它们的基本特性。记录是使用小鼠纵行肌肌间神经丛标本，通过膜片钳和尖锐的细胞内电极获得的。这些神经元具有动作电位驼峰和缓慢的后超极化（AHP）电流。缓慢的AHP是由对蝎毒素和克霉唑敏感的中等电导的钙依赖性钾通道电流所携带。所有神经元都具有一种可被细胞外铯阻断的超极化激活电流。它们还表达一种在静息电位附近起始的抗河豚毒素的钠电流。按压包含所记录神经元的神经节在17/18个细胞中诱发去极化电位。在突触传递被阻断后，这些电位仍然存在。一连串的突触前电刺激在9/11个感觉神经元中诱发缓慢的兴奋性突触后电位（EPSP），但0/29个细胞接受快速EPSP输入。缓慢的EPSP是由一种对电压不敏感的钾电流的去除所产生。使用含KMeSO4（而非常规的富含KCl）的细胞内溶液进行膜片钳记录，重现了用尖锐细胞内记录所观察到的单峰缓慢AHP和低输入电阻。对中等电导钾通道的细胞贴附式记录支持了单峰缓慢AHP是肠道AH/感觉神经元的一种固有特性这一结论。单通道电流记录也表明，缓慢的AHP电流可能对这些细胞中所见的高静息背景电导没有显著贡献。小鼠肌间感觉神经元特性的描述为研究它们在正常和病理生理学中的作用开辟了道路。