Tøttrup A, Svane D, Forman A
Department of Surgical Gastroenterology L, Aarhus Kommunehospital, Denmark.
Am J Physiol. 1991 Mar;260(3 Pt 1):G385-9. doi: 10.1152/ajpgi.1991.260.3.G385.
Strips from opossum lower esophageal sphincter were prepared and mounted in organ baths for recording of isometric tension. Nonadrenergic, non-cholinergic (NANC) inhibitory responses were evoked by transmural field stimulation. The relaxant responses to field stimulation were inhibited in a concentration-dependent manner by N omega-nitro-L-arginine (L-NNA), a substance known to inhibit the formation of nitric oxide (NO). At a concentration at 10(-4) M of L-NNA, most preparations contracted during field stimulation, and this response was abolished by atropine (10(-6) M). L-Arginine (10(-5) M) shifted the concentration-response curve for L-NNA to the right. Relaxant responses to VIP (10(-9) to 10(-6)M) and sodium nitroprusside (10(-9) to 10(-5) M) were unaffected by preincubation with L-NNA (10(-5) to 10(-4) M) or L-arginine (10(-5) M). The inhibition of NANC-relaxation was apparently not due to an influence on release of a NANC transmitter different from NO, since L-NNA had no preserving effects on responses to field stimulation in preparations treated with scorpion venom. We conclude that involvement of a NO-generating process from L-arginine seems mandatory for NANC responses in the isolated lower esophageal sphincter.
制备负鼠下食管括约肌条带，并将其安装在器官浴槽中以记录等长张力。通过跨壁场刺激诱发非肾上腺素能、非胆碱能（NANC）抑制反应。N-ω-硝基-L-精氨酸（L-NNA）是一种已知可抑制一氧化氮（NO）形成的物质，它以浓度依赖性方式抑制对场刺激的松弛反应。在L-NNA浓度为10⁻⁴ M时，大多数标本在场刺激期间收缩，而这种反应可被阿托品（10⁻⁶ M）消除。L-精氨酸（10⁻⁵ M）使L-NNA的浓度-反应曲线右移。对血管活性肠肽（10⁻⁹至10⁻⁶ M）和硝普钠（10⁻⁹至10⁻⁵ M）的松弛反应不受与L-NNA（10⁻⁵至10⁻⁴ M）或L-精氨酸（10⁻⁵ M）预孵育的影响。NANC松弛的抑制显然不是由于对与NO不同的NANC递质释放的影响，因为L-NNA对用蝎毒处理的标本中场刺激的反应没有保存作用。我们得出结论，在分离的下食管括约肌中，NANC反应似乎必须涉及由L-精氨酸生成NO的过程。
