Ohta D, Sarna S K, Condon R E, Lang I M
Department of Surgery, Medical College of Wisconsin, Milwaukee, USA.
Am J Physiol. 1996 Apr;270(4 Pt 1):G717-24. doi: 10.1152/ajpgi.1996.270.4.G717.
The effects of inhibition of nitric oxide (NO) synthase in the brain on colonic motor activity were investigated in conscious dogs. Intracerebroventricular (ICV) infusion of N omega-nitro-L-arginine methyl ester (L-NAME) and N omega-nitro-L-arginine (L-NNA) significantly suppressed colonic motor activity. The inhibitory effects occurred 1 h after the end of the infusion and lasted for at least 4 h. This suppression was blocked by a concurrent infusion of L-arginine but not D-arginine. The suppression of colonic motor activity was not blocked by bilateral truncal vagotomy or intravenous administration of phentolamine, an alpha-receptor antagonist, and propranolol, a beta-receptor antagonist. ICV infusion of L-NAME had no significant effect on the occurrence of giant migrating contractions in the colon. By contrast, intravenous administration of L-NAME at higher doses significantly enhanced colonic motor activity. We conclude that the inhibition of NO synthesis in the brain suppresses, whereas the inhibition of NO synthesis in peripheral neurons stimulates, colonic motor activity. The central effect may be mediated by a decrease in cerebral blood flow due to the inhibition of NO synthesis in cerebral arteries.
在清醒犬中研究了脑内一氧化氮（NO）合酶抑制对结肠运动活性的影响。脑室内（ICV）注入Nω-硝基-L-精氨酸甲酯（L-NAME）和Nω-硝基-L-精氨酸（L-NNA）可显著抑制结肠运动活性。抑制作用在注入结束后1小时出现，并持续至少4小时。同时注入L-精氨酸可阻断这种抑制作用，但D-精氨酸则不能。双侧迷走神经干切断术或静脉注射α受体拮抗剂酚妥拉明和β受体拮抗剂普萘洛尔均不能阻断结肠运动活性的抑制。ICV注入L-NAME对结肠中巨大移行性收缩的发生无显著影响。相比之下，较高剂量静脉注射L-NAME可显著增强结肠运动活性。我们得出结论，脑内NO合成的抑制会抑制结肠运动活性，而外周神经元中NO合成的抑制则会刺激结肠运动活性。中枢效应可能是由于脑动脉中NO合成受抑制导致脑血流量减少所介导的。
