Maczka M, Thor P, Bilski J, Konturek S J
Institute of Physiology, Faculty of Medicine, Jagiellonian University, Cracow, Poland.
J Physiol Pharmacol. 1994 Jun;45(2):285-98.
Intestinal motility and pancreatic secretion show synchronous cyclic changes (MMC) that are interrupted by feeding. The aim of this study was to determine the possible implication of nitric oxide (NO) (that was proposed as nonadrenergic noncholinergic neurotransmitter) in the motor and secretory components of MMC in 5 conscious dogs equipped with monopolar electrodes implanted along the small bowel and pancreatic fistulas. In fasted dogs with typical MMCs, L-NNA (an inhibitor of NO synthase) (5 mg/kg-h i.v.) decreased the MMC interval from control value of 80 +/- 7 to 60 +/- 4 min while increasing significantly the slow waves with spikes and suppressing the phase III-related increase in pancreatic secretion. Infusion of L-arginine (L-Arg) (a substrate of NO synthase) (10 mg/kg-h i.v.) increased the MMC interval from control 79 +/- 7 to 96 +/- 8 min and reduced the slow waves spikes by about 25%. Pancreatic secretion showed significant increase to about 20%. CCK maximum. Similar but transient effects were observed when glyceryl trinitrate (GTN) (a donor of NO) (1 mg/kg-h) was administered. After ingestion of meal, the MMC cycles were replaced by irregular spike activity with an average of about 35% slow waves with spikes and pancreatic secretion rose to about 70% of CCK maximum. Infusion of L-Arg (10 mg/kg-h) reduced by about 90% the postprandial spike activity but failed to affect significantly the pancreatic secretion. Also, injection of GTN (1 mg/kg-h) reduced the spike activity but did not influence pancreatic secretion. L-NNA in fed dogs caused an initial increase in spike activity followed by phase III and about 60% inhibition of pancreatic secretion. L-NNA added to L-Arg infusion reversed in part both intestinal motility and pancreatic secretory effects of L-Arg infusion. We conclude that NO system exerts a tonic inhibitory influence on intestinal myoelectric activity by reducing the frequency of MMC pacesetter and by suppressing the postprandial activity but stimulates pancreatic secretion.
肠道蠕动和胰腺分泌呈现同步的周期性变化（移行性复合运动，MMC），进食会打断这种变化。本研究的目的是确定一氧化氮（NO）（被认为是非肾上腺素能非胆碱能神经递质）在5只清醒犬的MMC运动和分泌成分中的可能作用，这些犬沿小肠植入了单极电极并建立了胰腺瘘管。在具有典型MMC的禁食犬中，L-NNA（一氧化氮合酶抑制剂）（5毫克/千克·小时，静脉注射）使MMC间隔从对照值80±7分钟缩短至60±4分钟，同时显著增加了伴有锋电位的慢波，并抑制了与Ⅲ期相关的胰腺分泌增加。输注L-精氨酸（L-Arg）（一氧化氮合酶的底物）（10毫克/千克·小时，静脉注射）使MMC间隔从对照的79±7分钟增加到96±8分钟，并使慢波锋电位减少约25%。胰腺分泌显著增加至约20%的CCK最大值。当给予硝酸甘油（GTN）（一种NO供体）（1毫克/千克·小时）时，观察到类似但短暂的效应。进食后，MMC周期被不规则的锋电位活动取代，平均约35%的慢波伴有锋电位，胰腺分泌上升至约70%的CCK最大值。输注L-Arg（10毫克/千克·小时）使餐后锋电位活动减少约90%，但未显著影响胰腺分泌。同样，注射GTN（1毫克/千克·小时）减少了锋电位活动，但未影响胰腺分泌。喂食犬中的L-NNA导致锋电位活动最初增加，随后出现Ⅲ期，并使胰腺分泌受到约60%的抑制。添加到L-Arg输注中的L-NNA部分逆转了L-Arg输注对肠道运动和胰腺分泌的影响。我们得出结论，NO系统通过降低MMC起搏点的频率和抑制餐后活动对肠道肌电活动发挥强直性抑制作用，但刺激胰腺分泌。
