Stark M E, Bauer A J, Sarr M G, Szurszewski J H
Department of Physiology and Biophysics, Mayo Clinic, Rochester, Minnesota.
Gastroenterology. 1993 Feb;104(2):398-409. doi: 10.1016/0016-5085(93)90407-4.
Nitric oxide (NO) may be an inhibitory neurotransmitter in the intestinal muscle. The present study examined its role in human and canine jejunum.
Mechanical and intracellular electrical activity were recorded simultaneously from the circular muscle layer.
In the human jejunum, nerve stimulation inhibited mechanical activity and evoked an inhibitory junction potential that consisted of an initial fast hyperpolarization followed by a late sustained hyperpolarization. NO inhibited mechanical activity and evoked a dose-dependent hyperpolarization that mimicked the late hyperpolarization. In the canine jejunum, nerve stimulation inhibited mechanical activity and evoked an inhibitory junction potential that consisted of only a fast hyperpolarization. NG-Monomethyl-L-arginine and NG-nitro-L-arginine attenuated nerve-mediated inhibition of mechanical activity in both species. However, the effect of the synthase inhibitors on inhibitory junction potentials differed in the two species. In canine jejunum, both inhibitors reduced the amplitude of the initial fast hyperpolarization. In human jejunum, both inhibitors reduced only the late sustained hyperpolarization.
NO mediates neural inhibition in circular muscle of both human and canine jejunum through different mechanisms.
一氧化氮（NO）可能是肠道肌肉中的一种抑制性神经递质。本研究探讨了其在人和犬空肠中的作用。
同时记录环形肌层的机械活动和细胞内电活动。
在人空肠中，神经刺激抑制机械活动并诱发抑制性接头电位，该电位由初始快速超极化和随后的晚期持续性超极化组成。NO抑制机械活动并诱发剂量依赖性超极化，该超极化模拟晚期超极化。在犬空肠中，神经刺激抑制机械活动并诱发抑制性接头电位，该电位仅由快速超极化组成。NG-单甲基-L-精氨酸和NG-硝基-L-精氨酸减弱了两种动物中神经介导的机械活动抑制。然而，合酶抑制剂对抑制性接头电位的影响在两种动物中有所不同。在犬空肠中，两种抑制剂均降低了初始快速超极化的幅度。在人空肠中，两种抑制剂仅降低了晚期持续性超极化。
NO通过不同机制介导人和犬空肠环形肌中的神经抑制。
