长春新碱对大鼠小肠肌电及动力的影响

目的 探讨抗肿瘤药长春新碱(VCR)对清醒大鼠小肠肌电和动力及相关机制的影响.方法 SD大鼠72只,分为6组,A组为对照组(n=18),尾静脉注射0.9%氯化钠溶液;B组为VCR尾静脉注射组,按给药剂量分为0.25 mg/kg(n=6)、0.5 mg/kg(n=6)和0.75 mg/kg(n=18)组;C组为假手术组(n=6),仅剖腹,尾静脉注射0.9%氯化钠溶液;D组为假手术+VCR 0.75 mg/kg(n=6);E组为双侧膈下迷走神经切断+0.9%氯化钠溶液(n=6);F组为双侧膈下迷走神经切断+VCR 0.75 mg/kg(n=6).观察用药后大鼠小肠的肌电及动力变化.采用生物机能实验系统记录小肠慢波频率、曲线下面积,移行性复合运动(MMC)周期、MMC Ⅲ相持续时间;测定小肠推进率,免疫荧光染色观察肠肌间神经元及Cajal间质细胞的表达.结果 VCR 0.25 mg/kg组对小肠动力无明显改变.0.5和0.75 mg/kg组均出现小肠肌电活动异常,且随作用时期不同表现不同,静脉注射(51.00±14.27)min后MMC模式被连续性峰电取代,(78.33±13.08)min后MMC逐渐恢复,0.5和0.75 mg/kg组MMC周期分别为(343.17±142.93)s和(302.67±66.67)s,较A组[(740.22±98.92)s]缩短(F=31.325,P<0.01).用药后第3天,0.5和0.75 mg/kg组曲线下面积为(2.56±0.30)mV·s和(2.57±0.56)mV·s,较A组降低[(4.04±0.64)mV·s,F=11.442,P<0.01].用药第3天,VCR 0.75 mg/kg组小肠推进率为(33.59±1.43)%,较A组减慢[(60.34±2.41)%,t=23.360,P<0.01].迷走神经切断组用药当日仍保持MMC相模式,第3天出现不规则峰电活动及慢波节律紊乱,VCR组曲线下面积为(2.49±0.33)mV·s,较A组降低[(4.10±0.80)mV·s,t=4.549,P=0.001].用药第3天,VCR 0.75 mg/kg组Cajal间质细胞阳性面积比为(5.84±3.11)%,较A组减少[(24.90±1.86)%,t=20.357,P<0.01];肠肌间神经元阳性面积比为(14.37±2.00)%,与A组比较差异无统计学意义[(14.17±2.63)%,P>0.05].结论 VCR改变小肠肌电活动及动力,并与剂量及时间相关.推测初期是通过迷走神经通路增强小肠运动,后期损伤Cajal间质细胞,导致小肠动力减弱.     

Effects of metoclopramide on gastrointestinal myoelectric activity in rats

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Effect of secretin on small bowel myoelectric activity of conscious healthy dogs

Myoelectric activity of the duodenum and small intestine of 7 dogs was studied over a period of 4 months using chronically implanted platinum electrodes. Secretin, 1 unit/kg body weight, reduced the incidence of bursts of action potentials without significant effect on the frequency or velocity of the pacesetter potential (slow wave). Inhibition of action potentials was greater in the duodenum and jejunum than in the ileum in all dogs studied. It is concluded that a gradient of diminishing inhibitory action of secretin on action potentials, and therefore on motor activity, extends distally throughout the small intestine.Supported in part by Research Grant AM-2015 from NIH, US Public Health Service.Read at the meeting of the American College of Surgeons, San Francisco, Oct 6–10, 1969.The authors thank Mr. J. C. Miller for technical assistance and Dr. W. F. Taylor and Mrs. Pamela Doctor of the Section of Medical Statistics, Epidemiology and Population Genetics, Mayo Clinic, for aiding in the statistical analysis of the results.Address for reprint requests: Section of Publications, Mayo Clinic, Rochester, Minn 55901.Recipient of a travelling fellowship from the Medical Research Council of Great Britain.     

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.     

Insulin and myoelectric activity of the small intestine of the pig

The effect of insulin on the myoelectric activity of the small intestine was determined in conscious pigs. Animals were implanted with electrodes along the small intestine, a strain gage on the stomach and catheters in both saphenous arteries. Feeding modified the migrating myoelectric complex (MMC), a cyclic pattern of action potential activity of the small intestine characteristic of fasting. The first period of regular spiking activity (RSA) on the duodenum after feeding was delayed and was not followed by quiescence. Plasma insulin and glucose concentrations during the first three MMC after feeding were highest just before periods of duodenal RSA. Injection or infusion of insulin into fasted pigs with production of hypoglycemia caused disruption of stomach motility and duodenal electrical activity. The duodenal MMC was not altered when glucose to prevent hypoglycemia was infused together with insulin or when glucose was infused alone. These studies suggest that insulin is not directly responsible for the postprandial modification of MMC activity as insulin infusions only modify the MMC when hypoglycemia occurs.A preliminary report of this work has been published as an abstract (1).     

Computer analysis of small-intestinal interdigestive myoelectric complex in dogs

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Vincristine alters myoelectric activity and transit of the small intestine in rats

We investigated the motility of the small intestine in unanesthetized rats receiving vincristine (0.075, 0.50, 0.75 mg/kg i.v.). Motility was determined by two methods: myoelectric activity was monitored with indwelling bipolar electrodes, and intestinal transit was measured by the movement of radiochromium (Na51CrO4). Only the animals injected with the two higher doses had two distinct patterns of altered intestinal myoelectric activity within 2 h of drug administration. The first alteration occurred 44 +/- 6 min after vincristine administration and consisted of a marked increase in action potential activity with disruption of the migrating myoelectric complex. The second alteration consisted of a reappearance of the activity front of the migrating myoelectric complex with a significantly shorter periodicity. A marked reduction in spike activity occurred 3 days after vincristine injection in 3 of 10 animals receiving vincristine. A biphasic response was noted in intestinal transit. Disrupted activity front formation was associated with a significant delay in small bowel transit. In contrast, frequent activity front formation in rats was associated with significantly hastened transit. In summary, vincristine administration induces alterations of myoelectric activity of the small intestine in fasted rats and is associated with changes in intestinal transit.     

Migrating myoelectric complex and jejunal slow-wave propagation after Roux gastrectomy in dogs

Roux-en-Y gastrectomy is associated with a high incidence of symptoms of gastric stasis. Retrograde propagation of jejunal electrical slow waves and spike bursts has been implicated in the Roux Y stasis syndrome. Since the fasted state may persist after feeding, this study examined the extent of retrograde slow-wave propagation in the fasted state, particularly during aboral migration of phase III. Six dogs underwent Roux gastrectomy and placement of bipolar electrodes along the Roux limb. Four normal dogs with electrodes acted as controls. Thirty-five migrating myoelectric complexes were recorded in Roux dogs and 13 in controls. In Roux dogs, the incidences of retrograde propagation of slow waves during the migrating myoelectric complex were phase I 56±13%, phase II 60±12% and phase III 58±14% (not significant). For controls, the incidences were 0%, 0%, and 1%, respectively (P<0.006 versus Roux dogs). In the Roux limb, retrograde propagation of slow waves, and hence spike bursts, occurs even during aboral migration of phase III. This abnormality may contribute to the Roux Y stasis syndrome.An abstract of this work has previously been presented at American Federation for Clinical Research Mid Western Section, October 31, 1990, at Chicago.Supported in part by a grant from the Veterans Administration and from the Department of Surgery, SUNY Health Science Center at Syracuse, Syracuse, New York.     

Myoelectrical and mechanical activity of stomach and intestine in hypothyroid dogs

Myoelectrical activity was studied in normothyroid and hypothyroid Labrador dogs in the resting state, following injection of pentagastrin, bethanechol chloride, and after feeding. Hypothyroidism was produced by total thyroidectomy and chronic treatment with thiouracil. Electrodes were surgically implanted over the serosa of the stomach, duodenum, jejunum, and ileum and used for repeated recording of myoelectrical activity of gastrointestinal muscles. A strain gauge was implanted over the gastric antrum and served to record mechanical activity of the stomach. As compared with control dogs, hypothyroid animals showed (a) decreased frequency of electrical control activity of the stomach and jejunum, (b) decreased occurrence of electrical response activity (spike potentials) following stimulation, and (c) decreased mechanical response to the same stimulants, ie, pentagastrin, bethanechol chloride, and food.This work was supported by Medical Research Council of Canada grant No. MA 4837.     

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...     

Are intraluminal electrodes reliable for recording myoelectric activity of the small intestine?

In humans except for the postoperative state, electromyographic activity of the small bowel can only be recorded with intraluminal electrodes. The aim of this study was to validate the use of intraluminal electrodes in pigs by comparing the signal recorded from such electrodes to those recorded with surgically implanted electrodes. A polyethylene probe equipped with bipolar ring-shaped electrodes was placed in the lumen of the proximal jejunum of 6 pigs, at the same level as intramuscular implanted electrodes. The signals were recorded in conscious pigs fed normally. By comparison to the myoelectric activity recorded from the intramuscular implanted electrodes, the intraluminal electrodes provided reliable spike burst detection (sensitivity 85 p. 100; positive predictive value 91 p. 100) in the fasted and fed state, and good identification of migrating myoelectric complexes. Spectral analysis showed the same frequency patterns for signals obtained with both types of electrodes. In conclusion, intraluminal ring-shaped electrodes allow reliable detection of small bowel myoelectric activity and may represent a useful tool for motility studies in man.     

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…     

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.     

Intestinal microflora stimulates myoelectric activity of rat small intestine by promoting cyclic initiation and aboral propagation of migrating myoelectric complex

Microbial modulation of myoelectric activity in small intestine was studied. Germ-free male Sprague-Dawley rats were equipped with bipolar electrodes from the duodenojejunal junction to the midpoint of small intestine. Prior to and one week after introduction of conventional intestinal microflora, 32±5% and 61±5% (mean±se), respectively, of activity fronts of the migrating myoelectric complex reached the midpoint (P<0.05), and the interval between activity fronts in proximal jejunum was reduced from 31.2±2.0 min to 17.5±0.8 min, respectively (P<0.01). The pattern of propagation was more regular after conventionalization. Slow-wave frequency in proximal jejunum was 38.5±1.2/min in germ-free rats and 43.0±0.8/min in conventional rats (P<0.01), but introduction of microflora failed to increase the frequency in germ-free rats. The frequency of spike potentials succeeding jejunal infusion of 5 ml of 12.5% glucose remained unchanged after conventionalization. Statistical analyses showed that the interval between activity fronts varied mainly within rats, whereas the propagation velocity showed statistically significant variability between rats (P<0.01), regardless of intestinal microflora. Luminal control by the resident microflora is important for physiological cycling and aboral propagation of the migrating myoelectric complex, but seems to be of no major consequence for postprandial myoelectric response.     

Alterations of myoelectric activity associated with Campylobacter jejuni and its cell-free filtrate in the small intestine of rabbits

We evaluated the effects of a culture of Campylobacter jejuni and its cell-free filtrate on myoelectric activity of isolated ileal segments in New Zealand White rabbits. Hematoxylin and eosin staining and scanning electron microscopy were used to assess the association between histologic changes and alterations in intestinal myoelectric activity. A culture of C. jejuni was shown to cause a significant increase in repetitive bursts of action potentials (RBAPs) (6.9 +/- 1.2 RBAP/h; p less than 0.001) compared with controls (0.3 +/- 0.1). Cell-free filtrates of C. jejuni cultures were also observed to induce RBAPs (5.0 +/- 0.9 RBAP/h; p less than 0.001). The fraction within the filtrate that induces alterations in motility was not destroyed by heating to 100 degrees C for 15 min (6.3 +/- 1.2 RBAP/h). Although no gross histologic changes were noted by hematoxylin and eosin staining of intestine exposed to a culture of C. jejuni for 8 h, blunting of villi with a cellular infiltrate was noted in rabbits exposed for 24 h. Scanning electron microscopy disclosed patchy villous tip damage in 3 of 5 animals exposed to cell-free filtrates for 8 h. These studies suggest C. jejuni is pathogenic and produces a heat-stable substance that alters intestinal myoelectric activity in rabbits.     

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。     

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.