Does irradiation produce irreversible changes in canine jejunal myoelectric activity?

We sought to determine whether acute irradiation-induced changes in jejunal myoelectric activity are reversible or chronic and progressive with repeated exposures. Five dogs underwent abdominal irradiation absorbing 938 cGy on four separate occasions, two weeks apart. Recordings of jejunal myoelectric activity were made before and 10–11 days after each irradiation exposure. Ten to 11 days after the first exposure, the animals recovered completely from the acute radiation syndrome, and the myoelectric activity returned to normal. After subsequent exposures, they developed chronic diarrhea, profound weight loss, and progressive changes in myoelectric activity. Slow waves exhibited highly variable configuration, had an irregular rhythm, and were frequently uncoupled. Spike burst activity, duration, and length of migration were reduced in association with abnormal motility patterns even though histologic abnormalities were mild. Such changes are likely to interfere with normal propulsion and contribute to impaired nutrition. The abnormalities suggest that irradiation causes dysfunction of one or more of the cellular elements involved in small bowel motility (muscle, nerve, and interstitial cells) prior to the development of severe histologic abnormalities or mechanical obstruction.Supported by medical research funds from the Department of Veterans Affairs.     

Effect of duodenal ulcerogens cysteamine,mepirizole, and MPTP on duodenal myoelectric activity in rats

Increased gastric acid secretion, enhanced acid delivery to the duodenum, and reduced alkaline secretion in the proximal duodenum are relatively well-established pathophysiologic abnormalities in duodenal ulcer. Impaired duodenal motility, however, may also contribute to duodenal ulceration by altering the distribution of acid and alkaline secretions along the upper digestive tract. We tested the hypothesis that the duodenal ulcerogens cysteamine, MPTP, and mepirizole modify duodenal motility in the rat and that motility changes might be a common and early alteration in experimental duodenal ulceration. All three duodenal ulcerogens rapidly produced extensive changes in duodenal myoelectric activity and reduced the frequency of myoelectric slow waves. Cysteamine induced marked hypermotility for at least 6 hr; MPTP rapidly decreased motility and fragmented the myoelectric migrating pattern. Mepirizole induced biphasic changes: an early hypermotility phase of about 30 min was followed by profound hypomotility. These results indicate that marked alterations of duodenal motility are common during experimental duodenal ulceration. In light of the differential effect of the ulcerogens on duodenal motility, it remains to be determined how these changes influence acid neutralization in the proximal duodenum. Nevertheless, our results suggest that all three duodenal ulcerogens, which are different in structure, alter duodenal motility.Dr. Mangla did this work while on sabbatical leave at Harvard Medical School.     

电针足三里穴对不完全性肠梗阻大鼠小肠肌电活动的影响

目的:探讨电针足三里穴对肠梗阻大鼠小肠肌电活动的影响.方法:采用非贯穿肠管的方式,末端回肠套环建立不完全性肠梗阻大鼠模型,将大鼠随机分为:空白对照组(n=10)、假手术组(n=10)、肠梗阻组(IO组,n=10)、肠梗阻+电针组(14dIO+EA组,n=10,21dIO+EA组,n=10).造模成功后空白对照组、假手术组、IO组均未给予电针治疗措施,IO+EA组连续给予电针14d、21d电针治疗措施.最后1次电针后2h,分别测体质量后打开腹腔,肉眼观察回肠组织形态学的改变,BL-420F生物机能实验系统测定回肠肌电.结果:IO组大鼠体质量较空白对照组和假手术组显著降低(P<0.01),IO+EA组大鼠体质量较IO组显著升高(P<0.01).回肠肌电慢波活动改变情况:14dIO组振幅(mV)低于空白对照组(0.11±0.03vs0.35±0.06,P<0.01),且频率(%)、振幅(%)变异系数均明显高于空白对照组和假手术组(27.71±10.54vs14.08±4.22,22.00±6.24;75.54±8.59vs15.84±1.49,20.67±7.57,均P<0.01);电针实验治疗IO+EA组大鼠14...     

Gastrointestinal myoelectric activity in an infant with congenital idiopathic motility disorder

We investigated myoelectric activity in an 8-month-old male who presented with a perinatal bowel obstruction, duodenal band, congenital short small intestine, and persistent feeding intolerance. Serosal electrodes were surgically implanted on stomach, duodenum, and jejunum during Nissen fundoplication and ileostomy. A 5-cm ileal specimen was taken for in vitro studies. Spontaneous migrating myoelectric complexes (MMC) were present in stomach and small intestine. Bethanechol increased electrical response activity (ERA) in stomach and duodenum. Morphine induced intense ERA and distinct phase III activity. Pentagastrin infusion did not disrupt MMC cycling. Feeding disrupted MMC complex cycling 30-40 min after the meal. Metoclopramide before feeding delayed disruption of the MMC cycling after the feeding. Intermittent gastric arrhythmias were present after the fifth postoperative day. In vitro muscle strips showed spontaneous contractions and electrical control activity (ECA). Bethanechol, McNeil A-343, motilin, and cholecystokinin induced contractions, but pentagastrin had no effect. We conclude that in spite of a major clinical motility dysfunction, several of our findings were normal. The abnormalities include short MMC period, absence of disruption of MMC by pentagastrin, and gastric arrhythmias.     

Computer analysis of small-intestinal interdigestive myoelectric complex in dogs

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Effects of neurotrophins on gastrointestinal myoelectric activities of rats

AIM: To observe the effects of mouse nerve growth factor (NGF), rat recombinant brain derived neurotrophic factor (rm-BDNF) and recombinant human neurotrophin-3 (rh-NT3) on the gastrointestinal motility and the migrating myoelectric complex (MMC) in rat.METHODS: A randomized, double-blinded, placebo-controlled experiment was performed. 5-7 days after we chronically implanted four or five bipolar silver electrodes on the stomach, duodenum, jejunum and colon, 21 experimental rats were coded and divided into 3 groups and injected NGF, rm-BDNF, rh-NT-3 or placebo respectively via tail vein activity was recorded 2 hours before and after the test substance infusions in these consciously fasting rats.RESULTS: The neurotrophins-induced pattern of activity was characterized by enhanced spiking activity of different amplitudes at all recording sites, especially in the colon. In the gastric antrum and intestine, only rh-NT-3 had increased effects on the demographic characteristics of electrical activities (P＜0.05), but did not affect the intervals of MMCs.In the colon, all the three kinds of neurotrophins could significantly increase the frequency, amplitude and duration levels of spike bursts, and also rh-NT-3 could prolong the intervals of MMC in the transverse colon (25±11 min vs 19±6 min, P＜0.05). In the distal colon rh-NT-3 could evoke phase Ⅲ-like activity and disrupt the MMC pattern, which was replaced by a continuously long spike bursts (LSB) and irregular spike activity (ISA) for 48±6 min.CONCLUSION: Exogenous neurotrophic factors can stimulate gut myoelectric activities in rats.     

Effect of cisplatin on myoelectric activity of the stomach and small intestine in dogs

The effect of cisplatin on interdigestive myoelectric activity (IDMA) of the gastric antrum, duodenum and jejunum, plasma concentration of motilin, and animal behavior was studied in seven conscious dogs with gastric cannulas and platinum electrodes implanted on the serosal surface of antrum and upper small intestine. Cisplatin given intravenously in a dose of 2 mg/kg resulted in complete interruption of IDMA and produced predominantly phase II-like activity, lasting as long as 24 hr. Six of the seven dogs exhibited retropropagation of spike bursts from the jejunum to the antrum which was accompanied by emesis. Retropropagation of spike bursts did not occur in one dog who did not exhibit emesis. In addition, abnormal spike bursts occurred frequently, including simultaneously occurring spike bursts in both duodenum and jejunum and nonpropagating short spike bursts in isolated segments of the upper small intestine. As phase III of IDMA disappeared, plasma motilin concentrations remained comparable to those in phase II of normal IDMA but without the cyclic increases. These studies indicate that cisplatin interrupts the regular cycle of IDMA as well as the plasma motilin cycle and produces retropropagation of spike bursts and abnormal spike bursts. These changes in both motility and plasma motilin levels may play a part in the mechanism of emesis induced by cisplatin in dogs.This work was supported in part by The Genesee Hospital Gastrointestinal Research Fund and by U.S. Public Health Service Research Grants CA11198 and CA11083.     

Trans-cutaneous electrogastrographic study of gastric myoelectric activity in transposed intrathoracic stomach after esophagectomy

We examined the feasibility of trans-cutaneous electrogastrography (EGG) in recording myoelectric activity of the transposed thoracic stomach after esophagectomy. Nineteen patients who had Ivor-Lewis esophagectomy were studied. The EGG signal was recorded using cutaneous electrodes placed over the lower sternum. Eleven patients who underwent total gastrectomy served as controls. Normal rhythm pattern (2.4-3.6 cpm > or = 70%) and power ratio (PR > or = 2) was observed in five and 12 patients, respectively, after esophagectomy. The observation of normal gastric rhythm was more frequent in the postprandial period in the esophagectomy group (median 42.6%vs. 7.4%, P = 0.01), and the PR was significantly higher (median 2.27 vs. 1.38, P = 0.013) than the gastrectomy group. Feeding further increased the prevalence of normal gastric slow wave in the esophagectomy group (median 14.8% to 42.6%, P = 0.002) and improved the stability of dominant frequency (median 78% to 67%, P = 0.015). We conclude that gastric myoelectric activities of thoracic transposed stomach can be detected from cutaneous sternal electrodes. This represented a preservation of gastric motility even when the stomach is pulled up to the thorax as a substitute for the esophagus.     

Effects of motilin and ursodeoxycholic acid on gastrointestinal myoelectric activity of different origins in fasted rats

AIM: To investigate gastrointestinal migrating myoelectric complex (MMC) and the effects of porcine motilin and ursodeoxycholic acid (UDCA) on MMC of gastrointestinal tract of different origins in fasted rats. METHODS: Three bipolar silver electrodes were chronically implanted on the antrum, duodenum and jejunum. Seven days later 24 experimental rats were divided into 2 groups. One group was injected with porcine motilin via sublingual vein at a dose of 20 microg/kg, the other group was perfused into stomach with UDCA. The gastrointestinal myoelectric activity was recorded 1 h before and 2 h after the test substance infusions into the rats. RESULTS: In all fasted rats a typical pattern of MMC was observed. Among the totally 68 activity fronts recorded in fasted rats under control, 67% started in duodenum, and 33% in antrum. MMC cycle duration and duration of phase III of antral origin were longer than those of duodenal origin. Administration of 20 microg/kg porcine motilin induced a premature antral phase III of antral origin. But perfusion into stomach with UDCA resulted in shorter MMC cycle duration, longer duration of phase III of duodenal origin, which were followed with shorter cycle duration and duration of antral phase III. CONCLUSION: In fasted rats, MMC could originate from antrum and duodenum respectively. The characteristics of MMC of different origins may contribute to the large variations within subjects. The mechanisms of different origins of phase III may be different. Porcine motilin and UDCA could affect MMC of different origins of the gastrointestinal tract in fasted state, respectively.     

Effects of caffeine on gastrointestinal myoelectric activity and colonic spike activity in dogs

BACKGROUND: Caffeine is known to produce various effects on the gastrointestinal tract. Few studies have, however, investigated the effects of caffeine on gastrointestinal myoelectric activity under physiologic conditions. The aims of this study were to investigate the effects of caffeine on colonic motility (spike activity) and gastric and jejunal slow waves in conscious dogs. METHODS: The study was performed in eight healthy female hound dogs (15-20 kg) in which one pair of electrodes was implanted on the serosa of the stomach, one pair on the proximal jejunum, and another pair on the ascending colon. The protocol consisted of a 60-min recording as base line and a 90-min recording after intravenous injection of saline, a low dose of caffeine (125 mg), or a high dose of caffeine (250 mg). RESULTS: In the colon there was a significant increase in the number of spike bursts per minute after the injection of both the low (6.69+/-1.27 versus 8.22+/-1.31, P < 0.05) and the high dose (4.38+/-1.23 versus 6.92+/-0.98, P < 0.05) of caffeine. The increase in the total energy of spikes per minute after the injection of the high dose of caffeine was significantly higher than that after the low dose of caffeine (41.2+/-14.6 versus 133.4+/-39.2, P < 0.05). The characteristics of the gastric and jejunal slow waves were, however, not affected by caffeine. CONCLUSION: Caffeine increases spike activity in the colon, and its effect may be dose-dependent. Gastric and jejunal slow waves are not affected by caffeine.     

Effect of metoclopramide on interdigestive myoelectric activity in the conscious dog

The effect of two-hour infusions of metoclopramide at five different doses on interdigestive intestinal electrical activity was studied in four conscious fasting dogs. Spike activity during the infusions was quantitatively compared with activity during preceding and following periods of saline infusion. The effect of the drug was the enhancement of spike activity during migrating myoelectric complexes (MMC) without disruption of the fasting pattern; the effect was most marked in the proximal small intestine and diminished distally. As in other published studies with metoclopramide, its effects were variable and not dose dependent. The enhancement of the MMC by an exogenous stimulus, not previously reported, provides indirect evidence for cholinergic mediation of cyclical motor activity, and also suggests a rational basis for therapy.This work was undertaken with the support of the Wellcome Trust, the Medical Research Council and the University of London Central Research Fund.     

实验性急性肝内胆汁淤积幼年大鼠胃肠消化间期移行性肌电复合波的变化

目的:探讨异硫氰酸萘酯(ANIT)所致刚断乳大鼠急性肝内胆汁淤积胃肠消化间期移行性肌电复合波(MMC)的变化.?方法:?56只刚断乳SD大鼠被随机分为正常对照组(n?=?16)、中毒组(n?=?40).?两组分别随机取8只在胃窦、十二指肠、空肠分别慢性埋置三对银丝电极;?其余大鼠同时行假手术.?术后7-10?d,?埋置电极组大鼠均在清醒、空腹、自由活动状态下记录胃肠道MMC.?中毒组按200?mg/kg一次性灌服ANIT诱发大鼠急性肝内胆汁淤积病变,?观察灌服ANIT后中毒组在48,?96,?144,?192?h胆汁流量、血中TB和ALT值及胃肠MMC的变化.?结果:中毒组灌服ANIT后,?48?h时胆汁流量中断,?血清TB和ALT明显升高;?48?h后其胆汁流量逐渐增加,?血清TB和ALT逐渐下降,?于192?h基本恢复.?在ANIT灌胃前,?埋置电极的所有大鼠在清醒、禁食状态下均记录到典型的MMC节律性电活动,?正常对照组与中毒组之间差异无显著性意义;?中毒组灌服ANIT后,?MMC节律完全消失,?代之以Ⅱ期样节律紊乱波;?144?h后,?中毒组MMC节律运动开始恢复;?192?h时中毒组MMC均为节律运动,?但中毒组MMC持续时间(911.67±140.47?s)较正常对照组(682.87±77.39?s)明显延长,?其中主要是Ⅱ期持续时间延长(414.12±69.21?vs?150.28±35.45?s),?而Ⅲ期持续时间略缩短(121.21±27.38?s?vs?170.27±38.98?s)?,?差异有显著意义(P<0.05).结论:?急性肝内胆汁淤积时胃肠MMC表现MMC节律短暂消失或MMC周期延长;?其部分原因可能与消化间期胆汁流量减少有关.     

Effects of Jiawei Sijunzi Decoction on migrating myoelectric complex in 8.0 Gy irradiated rats

AIM: To investigate the changes of small intestinal migrating myoelectric complex (MMC) and regulatory effect of Jiawei Sijunzi Decoction in 8.0 Gy irradiated rats. METHODS: The MMC of the intestine of rats was recorded using chronically implanted electrodes at different parts of the small intestine to analyse duration of four phases of MMC and its cycle before and after irradiation and to investigate the regulatory effect of Jiawei Sijunzi Decoction. RESULTS: From 1 h to 7 d after 8.0 Gy irradiation the MMC cycle in most of rats disappeared and only phase II existed with minute’s rhythm. From 1 h to 3 d after irradiation, the MMC cycle appeared in a few rats with the duration of phase II shortened significantly (P < 0.05). Results of observation on effects of Jiawei Sijunzi Decoction on MMC after irradiation showed that the changes in phase and cycle of MMC were normalized basically by medication. CONCLUSION: Jiawei Sijunzi Decoction can improve the intestinal disturbances caused by radiation, and this might be one of the reasons for its alleviating effect on radiation induced diarrhea.     

Effect of electroacupuncture at Sibai on the gastric myoelectric activities of denervated rats

AIM: To explore the mechanism of the exciting effects of electro-acupuncture (EA) at Sibai on the gastric myoelectric activities. METHODS: A total of 32 rats were randomly divided into four groups. Through intraperitoneal injection with atropine (the anti-cholinergic agent by blockade of muscarinic receptors), hexamethonium (automatic nerve ganglion-blocking agent) and reserpine (anti-adrenergic agent by depleting the adrenergic nerve terminal of its norepinephrine store), effects of EA at Sibai on the gastric myoelectric activities of the denervated rats were observed. RESULTS: After intraperitoneal injection of atropine and hexamethonium, the average amplitude and ratio of period to time in the phase of high activity of gastric myoelectric slow wave, and the average numbers of the peaks of gastric myoelectric fast wave were significantly decreased (P<0.01, P<0.05, P<0.01), while after intraperitoneal injection of reserpine, the aforementioned three parameters were increased (P<0.01, P<0.05, P<0.01). EA at Sibai point partially relieved the inhibitory effect of atropine and hexamethonium on the gastric myoelectric activities in the rats (P<0.05 or P>0.05). CONCLUSION: Cholinergic and adrenergic nervous systems and autonomic nerve ganglion participate in the peripheral passage of the controlling effects of EA at Foot Yangming Channel on gastrointestinal tract.     

Effect of electroacupuncture at Sibai on the gastric myoelectric acitivities of denervated rats

INTRODUCTIONElectroacupuncture (EA) at certain points always exhibits marked effects (inhibitory or stimulatory) on organ activities. Our previous studies indicated that EA at the Sibai point exhibited exciting effects on gastric myoelectric activities. T…     

Myoelectric activity during chronic small bowel allograft rejection in rats

The aim of this study was to analyze the effect of chronic rejection on myoelectric activity of orthotopic small intestine transplants in vivo. Chronic rejection was achieved in orthotopic small bowel allografts (ACI-Lewis) using cyclosporin A for limited immunosuppression. Isogeneic transplants (ACI–ACI) as well as native bowels (ACI) with and without immunosuppression served as controls. Myoelectric activities were recorded after a 12-hr fasting period and analyzed visually. Pacemaker frequencies within grafts were significantly below normal values (group 1: 37; group 2: 31.7; group 3: 37; group 4: 32.3). MMC periods and MMC phases did not show significant differences. The propagation velocity of phase III contractions was elevated in the ileum of grafts undergoing chronic rejection (group 1: 1.79; group 2: 1.59; group 3: 2; group 4: 2.5). In conclusion, fasting motility is altered but preserved in intestinal allografts undergoing chronic rejection. Intrinsic reinnervation from the native duodenum, which is necessary to generate normal pacemaker frequencies, was observed neither in allografts nor in isografts after a three-month period.     

Effects of anesthesia and surgical procedures on intestinal myoelectric activity in rats

Electrical spiking activity of the duodenum and jejunum was recorded from chronically implanted electrodes in rats during volatile or barbiturate anesthesia and following laparotomy. The normal pattern of electrical spiking activity in the fasted rat, with myoelectric complexes at 15-min intervals, was transiently replaced by quiescence during ethyl ether anesthesia. A slight increase in irregular spiking activity occurred after induction with pentobarbital, and the only effect of thiopental anesthesia was a reduction in the velocity of propagation of the complexes by 20%. Under barbiturate anesthesia, incision of the skin did not inhibit myoelectric activity, but incision of each abdominal muscle layer had an immediate and transient inhibitory effect; the deeper the layer, the longer was the inhibition. Peritoneal incision consistently produced inhibition of spiking activity which was prolonged by exposure of the bowel to air and intestine handling. The inhibitory effects produced by surgery persisted after vagotomy or transection of the spinal cord at the thoracic level but disappeared after splanchnicectomy. The above results suggest that a somatovegetative reflex with efferent pathways in the splanchnic nerves is involved in the first stage of operative inhibition of intestinal myoelectric complexes.     

力胃颗粒对胃肠动力的影响

目的 观察力胃颗粒对实验动物胃肠动力的影响。方法 通过测定力胃颗粒对动物胃排空、肠推进及胃内压力的影响,研究其促胃肠动力作用．给小鼠ig饲料糊,观察力胃颗粒ig对胃排空率的影响;给小鼠ig炭末,观察力胃颗粒ig对肠推进率的影响;给小鼠ip盐酸多巴胺导致小鼠胃排空延迟,观察力胃颗粒ig对胃内酚红残留率的影响;给小鼠ip盐酸多巴胺导致小鼠肠胃反流,观察力胃颗粒id对胃内酚红残留率及肠胃反流量的影响;利用胃内安置水囊法观察力胃颗粒id对胃内压的影响。结果 力胃颗粒10g／kg及5g/kg可显著抑制小鼠饲料糊胃排空,胃排空率分别为(43．8±13,9)％及(44．7±20．2)％,与空白对照组(61.4±12．9)％比,均P     

胆汁返流性胃炎胃窦平滑肌电的研究

目的:研究表明,胆汁返流性胃炎有严重的胃排空障碍,本文着重探讨胃窦平滑肌电生理水平上的改变在胆汁返流性胃炎中可能的发病意义。方法:对13例胆汁返流性胃炎(R组),10例非胆汁返流性胃炎(N组)和7名健康志愿者(C组)的胃窦平滑肌电连续检测30分钟以上,比较平均慢波频率和胃节律紊乱的发生率和节律异常的严重程度。结果:各组平均慢波频率无显著性差异,但三组均可见胃节律异常,发病率在R组较高,为53.8％(7/13),C组和N组较低,分别为14.3％(1/7)和30.0％(3/10);程度上R组>N组>C组。结论:严重的胃窦平滑肌电节律紊可能是胆汁返流性胃炎发病的一个重要因素。