Stoner M C, Kellum J M
Virginia Commonwealth University, Department of Surgery, Richmond, VA, USA.
Surgery. 2001 Aug;130(2):236-41. doi: 10.1067/msy.2001.115903.
Previous studies have demonstrated that an antagonist of nitric oxide synthase inhibits neurally mediated chloride secretion in response to serotonin (5-HT). The purpose of this study was to demonstrate that chloride secretion in rat colonocytes that were caused by stimulation of neural 5-HT receptors is mediated by way of a nitrergic pathway that involves the activation of guanylate cyclase.
The nitric oxide (NO) donor, diethylenetriamine/NO (DNO), was added to an enriched suspension of rat colonocytes that were preloaded with (36)Cl(-). In parallel experiments, DNO (1 micromol/L) was added to cells that were pretreated with the specific inhibitor of soluble guanylate cyclase, NS2028 (2 micromol/L). In additional studies, the neural 5-HT(3) receptor agonist, 2-methyl-5-HT (10 micromol/L), was added to the serosal surface of muscle-stripped sheets of rat colonic mucosa that were mounted in Ussing chambers under voltage clamp conditions, both in the absence and presence of NS2028 (20 mircro).
DNO induced 18.0% +/- 8.0% greater (36)Cl(-) efflux than controls (P <.05; n = 14 animals). This efflux was abolished by previous treatment with NS2028. In the chamber experiments, 2-methyl-5-HT induced electrogenic chloride secretion that was significantly inhibited by previous treatment with NS2028 (2.2 +/- 0.5 microA/cm(2) vs 13.1 +/- 2.1 microA/cm(2); P <.001; n = 9 animals).
The predominant secretomotor neurotransmitter that mediates the chloride secretory effects of 5-HT in vitro is nitric oxide. Both the secretory effect initiated at the 5-HT(3) receptor on enteric neurons and at the NO(-) receptor on the rat colonocytes are mediated through the activation of intracellular guanylate cyclase and the production of cyclic guanosine monophosphate.
先前的研究表明，一氧化氮合酶拮抗剂可抑制神经介导的氯离子对血清素（5-羟色胺，5-HT）的分泌反应。本研究的目的是证明，神经5-HT受体受刺激后大鼠结肠细胞中的氯离子分泌是通过涉及鸟苷酸环化酶激活的一氧化氮能途径介导的。
将一氧化氮（NO）供体二亚乙基三胺/NO（DNO）添加到预先加载了（36）Cl（-）的大鼠结肠细胞富集悬浮液中。在平行实验中，将DNO（1微摩尔/升）添加到用可溶性鸟苷酸环化酶特异性抑制剂NS2028（2微摩尔/升）预处理的细胞中。在其他研究中，将神经5-HT（3）受体激动剂2-甲基-5-HT（10微摩尔/升）添加到在电压钳制条件下安装在尤斯灌流小室中的大鼠结肠黏膜肌肉剥离片的浆膜表面，有无NS2028（20微克）均进行此操作。
DNO诱导的（36）Cl（-）流出比对照高18.0%±8.0%（P<.05；n = 14只动物）。NS2028预先处理可消除这种流出。在小室实验中，2-甲基-5-HT诱导的电生性氯离子分泌被NS2028预先处理显著抑制（2.2±0.5微安/平方厘米对13.1±2.1微安/平方厘米；P<.001；n = 9只动物）。
在体外介导5-HT氯离子分泌作用的主要分泌运动神经递质是一氧化氮。在肠神经元上的5-HT（3）受体和大鼠结肠细胞上的NO（-）受体引发的分泌作用均通过细胞内鸟苷酸环化酶的激活和环磷酸鸟苷的产生介导。
