Study on functional constipation and constipation‐predominant irritable bowel syndrome by using the colonic transit test and anorectal manometry

OBJECTIVE: To investigate the visceral perception, anorectal pressure and colonic transit time (CTT) in patients with functional constipation and constipation‐predominant irritable bowel syndrome (C‐IBS), and to study the manometric abnormalities of these two conditions. METHODS: The CTT in patients with functional constipation and C‐IBS was studied by using radiopaque markers. Rectal visceral perception thresholds, rectal compliance and anorectal pressure were examined by electric barostat. RESULTS: The CTT in both groups of constipated patients was abnormal. A lot of radiopaque markers remained in the right colon in C‐IBS patients, whereas in patients with functional constipation, the radiopaque markers remained in each segment of the colon. The anorectal resting pressure, squeezing pressure and relaxation pressure were normal in both groups. Rectal compliance and defecation thresholds were much higher compared with controls, and the rectal visceral perception of functional constipation was also abnormal. CONCLUSIONS: The motility abnormalities of functional constipation and C‐IBS occurred in different colonic segments. Results suggest that CTT measure­ment and anorectal manometry could be helpful in the differential diagnosis of these two conditions.     

Anorectal dysfunction and delayed colonic transit in patients with progressive systemic sclerosis

We studied 14 unselected patients with progressive systemic sclerosis (PSS), six with constipation, and eight with normal bowel habits. A control group, matched for age and sex, comprised six patients with idiopathic constipation and seven healthy subjects. Anorectal manometry was performed with perfused catheters and segmental colonic transit was measured by a radiopaque marker technique. The resting pressure of the anal canal was significantly reduced in PSS with constipation (P<0.05). The rectoanal inhibitory reflex was detected in only one PSS patient with constipation, but was present in seven of eight PSS patients with normal bowel habits and in all controls (P<0.01). Total and right colonic transit times were significantly delayed in PSS with constipation and in patients with idiopathic constipation (P<0.05). In patients with PSS, colonic transit was delayed and anal sphincter function was impaired in constipated patients, suggesting involvement of both the colon and the anorectum by the disease.     

慢性便秘的分型和肛门直肠测压表现

目的：对慢性便秘按结肠传输时间（CTT）和传输指数（TI）进行分型,观察便秘及便秘各型肛门直肠动力学和敏感功能的变化。方法：采用一次口服20枚不透X线标记物于72h拍摄腹平片的方法,根据CTT和TI对慢性便秘进行传输分型;用肛门直肠测压的方法测定不同类型便秘的肛门直肠动力及感觉功能的变化。结果：慢性便秘的传输分型为四型：传输时间正常型（NTC）、慢传输型（STC）、出口梗阻型（OOC）和混合型（MC）。便秘组的肛管静息压和收缩压降低,最大耐受容积增大（P＜0．05）。NTC患者肛管静息压降低（P＜0．05）;STC患者静息压、收缩压降低,最大耐受容积增大（P＜0．05）;OOC患者最大耐受容积增大（P＜0．05）。结论：此种传输试验方法更简单;根据CTT和TI对便秘进行传输分型可体现便秘的动力学原因;不同类型的便秘存在不同的结肠、肛门直肠动力学改变和直肠感觉异常。     

Radiopaque markers transit and anorectal manometry in 16 patients with multiple sclerosis and urinary bladder dysfunction

Fecal incontinence and/or constipation are frequent complaints in multiple sclerosis associated with urinary bladder dysfunction, incontinence, and/or retention. Total and segmental colonic transit were studied by determination of radiopaque markers, and anorectal function by anorectal manometry, in 16 multiple sclerosis patients clinically defined (with urinary bladder dysfunction shown by urodynamic examination). Fifteen multiple sclerosis patients had constipation and 14 had increased colonic transit time; ten multiple sclerosis patients had fecal incontinence and five had spontaneous rectal contractions. It is suggested that increased colonic transit and anorectal dysfunction were secondary to neurologic disorders just as urinary bladder dysfunction is due to neurologic disorders in multiple sclerosis.     

回直肠吻合分流术对慢传输型便秘大鼠血浆SP及VIP的影响

目的:完成STC大鼠回肠直肠吻合分流手术,观察该术式对STC大鼠血浆SP、VIP的影响.方法:72只SD大鼠,随机取10只作为正常对照组,其余62只用大黄小剂量递增灌胃造模.造模过程中死亡5只,剩余57只,手术前处死12只作为模型对照组.剩余的45只大鼠,随机35只手术组,10只自然恢复组,测定并比较各组大鼠血浆中SP及VIP的含量.结果:SP水平:与正常对照组相比,模型组大鼠血浆SP水平显著降低(63.364±4.211vs81.032±4.237,P<0.01);恢复组对比模型组SP水平降低显著(50.138±5.283vs63.364±4.211,P<0.01);术后1mo,手术组对比恢复组数值增高(58.165±6.592vs50.138±5.283,P<0.05);但仍然低于模型组(58.165±6.592vs63.364±4.211,P<0.05).VIP水平:与正常对照组相比,模型组大鼠血浆VIP水平显著升高(32.152±6.204vs25.469±4.523,P<0.01);恢复组较模型组下降(25.217±3.517vs32.152±6.204,P<0.05),且与正常对照组无显著差异.手术组对比恢复组无显著差异.结论:回直肠吻合分流术明显改善STC大鼠的便秘症状,减轻结肠负担后能减轻结肠功能的进一步恶化,但能否促进大鼠结肠功能恢复尚待进一步研究.     

Gastrointestinal peptide hormones during postoperative ileus

The hypothesis was that postoperative ileus might be caused by a disturbed balance between the motor-stimulating hormones, motilin and substance P, and the motorinhibitory hormone, vasoactive intestinal polypeptide, and that octreotide might prevent this disturbance and so ameliorate the ileus. In 15 conscious dogs with chronic gastro-intestinal electrodes, electrical activity was recorded and blood was drawn for radioimmunoassay of motilin, substance P, and vasoactive intestinal peptide (VIP) during fasting and after a liquid meal. Ileus was then induced by celiotomy and intestinal abrasion. During and after operation, five dogs received 154 mM NaCl only, five dogs octreotide, 0.19 µg/kg/hr, and five octreotide, 0.83 µg/kg/hr. Plasma levels of motilin, substance P, and VIP were changed little by operation, but cyclical increases in plasma motilin, which occurred preoperatively during phase III of the interdigestive myoelectric complex, were completely abolished postoperatively during ileus, as was the complex itself. Octreotide ameliorated the ileus and restored the interdigestive complexes, but it decreased plasma motilin and did not restore the cyclic increases in motilin found in health, nor did it alter plasma substance P and VIP. In conclusion, octreotide ameliorates postoperative ileus, but it does not do so by increasing plasma motilin or substance P or decreasing plasma VIP.This work was supported by USPHS NIH grants DK18278 and DK07198, a grant from Sandoz Pharmaceuticals, and the Mayo Foundation.An abstract of this work has been published inGastroenterology 103:1382, 1992, and was presented at the biennial meeting of the American Motility Society, September 13–17, 1992, in Lake Tahoe, California.     

脑卒中急性期胃肠功能障碍患者血浆VIP水平变化的相关性研究

目的了解脑卒中患者急性期血浆血管活性肠肽(VIP)水平的动态变化,探讨血管活性肠肽与脑卒中急性期继发胃肠功能障碍的相关性。方法应用放射免疫法检测192急性脑卒中患者入院24 h及入院1周时血浆血管活性肠肽水平,并与51名健康对照组比较。结果脑卒中急性期继发胃肠功能障碍患者VIP水平入院2 4 h(2 0 6.0 1±9.8 6)pg/mL及入院1周时(1 7 7.6 3±8.82)pg/mL血浆,较对照组(138.76±8.96)pg/mL显著偏高(P<0.01)。胃肠出血组入院1周时VIP水平与对照组相比未见统计学意义(P>0.05),而非胃肠出血组入院1周时VIP水平仍高于对照组。结论血浆高VIP水平与脑卒中急性期继发的胃肠功能障碍具有一定的相关性。不同的胃肠症状表现形式可能与VIP升降的幅度有关。     

Distal stomach appears essential in the regulation of gastrointestinal transit

Stomach and small bowel both influence gastrointestinal motility. We studied which portion of the stomach was essential for the regulation of gastrointestinal movement and determined the role of vasoactive intestinal polypeptide in this regulation. The study subjects consisted of 45 controls, 46 patients after subtotal gastrectomy, and 13 patients after total gastrectomy for stomach cancer. Orocecal transit time was measured, using the hydrogen breath test, to represent gastrointestinal movement, while plasma vasoactive intestinal polypeptide level was simultaneously assessed. The orocecal transit times in the study groups were (means ± SD) 91.1 ± 45.0, 57.1 ± 34.3, and 60.8 ± 34.8 min, respectively (P < 0.01). In the subtotal gastrectomy patients, age showed a negative correlation with orocecal transit time (r = −0.388; P < 0.01). In the total gastrectomy patients, no particular demographic factor influenced orocecal transit. Plasma vasoactive intestinal polypeptide levels in the three groups were 20.7 ± 10.8, 22.7 ± 10.9, and 20.6 ± 9.1 pg/ml, respectively (NS). We conclude that both types of gastrectomies enhanced gastrointestinal movement, showing a similar effect, and that the distal stomach plus pylorus are most likely to exert an important inhibitory mechanism in the regulation of this movement. Vasoactive intestinal polypeptide is not a major peptide mediating this regulation. Received: August 9, 1999 / Accepted: November 26, 1999     

慢传输型便秘乙状结肠VIP,SP免疫组化研究

目的探讨慢传输型便秘（ＳＴＣ）的神经病理学基础。方法应用半定量免疫细胞组织化学的方法，对１４例ＳＴＣ和１１例非梗阻性直肠腺癌患者的乙状结肠标本进行研究，主要观察肠壁内血管活性肠肽（ＶＩＰ）和Ｐ物质（ＳＰ）的变化。结果常规ＨＥ染色下，两组结肠肌间神经丛无明显改变；免疫组化见ＳＴＣ患者乙状结肠壁内ＶＩＰ含量减少（Ｐ＜０．０５）；ＳＰ含量明显降低（Ｐ＜０．００１）；而粘膜层内无明显变化。结论ＳＴＣ患者结肠壁存在明显的神经病理学变化，其结肠传输减慢可能与肠壁内ＶＩＰ和ＳＰ能神经元数量减少和／或功能障碍有关。     

Changes in the somatostatin,substance P and vasoactive intestinal polypeptide content of the gastrointestinal tract following streptozotocin-induced diabetes in the rat

Summary Rats with streptozotocin-induced diabetes of 10 weeks' duration showed significant changes in the total content of somatostatin, substance P and vasoactive intestinal polypeptide in the stomach and small intestine compared with control animals. An increase (p<0.05) in the concentration and total content of gastric somatostatin and a decrease (p<0.05) in the concentration and content of gastric substance P were seen in the streptozotocin-treated rats. The increase in the vasoactive intestinal polypeptide (VIP) content (54%, p<0.05) and the decrease in the substance P content (35%, p<0.05) of the gut may contribute to the impaired intestinal motility observed in animals with experimentally produced diabetes. Both the diabetogenic effect of streptozotocin and the changes in regulatory peptide concentrations were prevented by injection of nicotinamide before streptozotocin suggesting that the changes did not arise from a non-specific toxic effect of streptozotocin upon gastrointestinal neurones and/or endocrine cells.     

疏肝润肠方防治慢传输型便秘可能机制及效应靶点的探讨

[目的]探讨疏肝润肠方干预慢传输型便秘可能机制及效应靶点.[方法]60只SPF级Balb/c雄性小鼠,按体质量随机分为:正常组、模型组、治疗组(含低、中、高剂量亚组).除正常组外,模型组、治疗组均以复方地芬诺酯灌胃制模.观察所有小鼠排便时间、排便次数及粪重,应用免疫组化SABC法检测Cajal细胞标志物C-kit表达,实时荧光定量PCR技术检测血浆中P物质(SP)和血管活性肠肽(VIP) mRNA表达变化.[结果]模型组大便次数减少、排便时间延长、粪便少而且硬;治疗组较模型组大便次数增加、排便时间缩短、大便性状偏软(P＜0.05).与正常组比较,模型组小鼠结肠黏膜Cajal细胞阳性分布面积及数目减少(P＜0.05).模型组小鼠结肠SP、VIP mRNA表达呈下降趋势;治疗组小鼠结肠SP、VIP mRNA表达呈上升趋势(P＜0.05).[结论]疏肝润肠方可能通过调控SP及VIP的分泌,从而缩短慢传输型便秘小鼠排便时间、增加排便次数及便重、促进小鼠粪便软化,增加肠推进,促进小肠的传输功能而发挥其治疗慢传输型便秘的药效.     

Gastrointestinal dysmotility in patients with acute pancreatitis

BACKGROUND AND AIMS: Gut-origin bacterial translocation is one of the major causes of pancreatic necrotic tissue infection in patients with severe acute pancreatitis (SAP). The gastrointestinal dysmotility is supposed to be the fundamental event in this process. To test this hypothesis, alteration of colonic transit time (CTT) in patients with acute pancreatitis (AP) was investigated. In order to evaluate the possible mechanisms involved in gastrointestinal dysmotility, changes of serum motilin (MTL), cholecystokinin (CCK) and vasoactive intestinal peptide (VIP) in patients with AP were also measured. METHODS: Twenty-four non-consecutive patients with AP and 25 controls were included in this study. The diagnosis of AP was based upon clinical features, biochemical indices and radiological investigation. The severity of AP at admission was evaluated according to the APACHE-II and Balthazar computed tomography (CT) scoring system. Total and segmental CTT in patients with AP and in controls were determined by ingestion of radiopaque markers (Sitzmarks(R)) according to the modified Metcalf's method. Meanwhile, serum MTL and CCK were assessed using radioimmunoassay (RIA), and serum VIP was measured by using ELISA in this study. RESULTS: Compared to the controls, the total CTT and segmental CTT (mainly right and left hemicolon) were prolonged significantly in 10 patients with SAP and 14 patients with MAP; P < 0.05. Moreover, the total CTT and segmental CTT were markedly more delayed in patients with SAP than in patients with MAP; P < 0.05. The concentrations of serum MTL and CCK were significantly decreased in both MAP and SAP patients compared with those in controls (P < 0.01). There was no significant differences in serum MTL and CCK levels between the SAP and MAP groups; P > 0.05. In addition, the concentration of serum VIP was increased in AP patients, and it reached statistical significance in patients with SAP (P < 0.05). CONCLUSIONS: In conclusion, gastrointestinal dysmotility often occurred in patients with AP, especially more severely in SAP patients. One of the possible mechanisms might be related to the synergic actions of gut hormones, such as MTL, CCK and VIP.     

帕金森病伴便秘与功能性便秘的直肠肛门测压特点分析

 目的观察帕金森病(PD)伴便秘患者与功能性便秘(FC)患者的直肠肛门动力和感觉功能及其异同。方法顺序纳入男性PD伴便秘患者15例及男性FC患者45例,均经全结肠镜或结肠钡灌肠除外肠道器质性疾病。经直肠肛门测压,分析患者直肠肛门动力参数及感觉参数,将排便障碍患者进一步分为排便协同障碍(F3a)及排便推进力不足(F3b)两种亚型。结果PD伴便秘组年龄(70±11)岁,FC组年龄为(68±11)岁,差异无统计学意义。PD伴便秘组直肠静息压较FC组偏高[9.0(4.0,15.0)mmHg比6.0(3.0,9.5)mmHg,1mmHg=0.133kPa],但差异无统计学意义(P=0.082);两组肛管静息压的差异无统计学意义[(51.2±17.2)mmHg比(59.7±20.4)mmHg,P=0.152]。缩紧肛门时,PD伴便秘组的肛管最大缩榨压及持续缩榨曲线下面积均显著低于FC组[(136.9±43.8)mmHg比(183.0±62.1)mmHg,P=0.010;(823.5±635.7)mmHg·s比(1392.4±939.9)mmHg·s,P=0.033]。模拟排便时,PD伴便秘组的直肠力排压及肛管力排剩余压也明显低于FC组[22.0(15.0,30.0)mmHg比42.0(31.0,55.0)mmHg,P=0.000;(46.3±23.3)mmHg比(77.9±35.1)mmHg,P=0.002];两组力排时的直肠肛管压差均为负值,异于正常排便压差,但两组间差异无统计学意义。PD伴便秘患者排便障碍以F3b型为主(10/15);FC组中以F3a型多见[46.7%(21/45)];但两组的排便障碍类型构成比的差异无统计学意义(P=0.120)。PD伴便秘患者及FC患者的直肠扩张初始感觉阈值分别为(91.3±56.9)ml与(67.2±38.9)ml,均高于正常参考值,但两组间差异尚无统计学意义(P=0.074)。结论PD伴便秘患者及FC患者均存在直肠肛门动力和感觉异常。与FC患者相比,PD伴便秘患者的缩肛及力排的重要参数值明显降低,且测压分型以F3b型为主,感觉阈值有升高趋势。上述指标可作为PD伴便秘患者直肠肛门测压的特征参数,对PD发病机制的理解及其与相关疾病的鉴别可起重要作用。     

Vasoactive intestinal polypeptide appears to be one of the mediators in misoprostol-enhanced small intestinal transit in rats

BACKGROUND AND AIMS: Prostaglandin analogs have the pharmacologic effect of speeding up small intestinal transit (SIT). It remains unknown whether some gut peptides also mediate this enhancement. We studied the effect of misoprostol on rat SIT and looked at the role of vasoactive intestinal polypeptide (VIP) release during its action. METHODS: A group of rats initially received oral misoprostol treatment of 1, 10, 50 and 100 microg/kg, respectively. By using orally fed charcoal as a motility marker, the SIT was assessed at 30 min following oral misoprostol treatment. Another group of rats received misoprostol as an intraperitoneal injection in similar doses to the group above. The small intestinal transit was computed for this group at 30 min following misoprostol injection via an instilled radiochromium motility marker that went through a previously placed intraduodenal catheter. The plasma VIP level was measured by using a radioimmunoassay kit. RESULTS: Neither charcoal evaluated transit nor the plasma VIP level was influenced by the lower doses of oral misoprostol treatment (1 and 10 microg/kg), whereas other doses enhanced SIT and diminished the plasma VIP level (P< 0.01).The similar effects on radiochromium computed SIT (P< 0.01) and plasma VIP levels were obtained in tubed rats following misoprostol intraperitoneal treatment. The SIT results correlated negatively with plasma VIP levels. CONCLUSIONS: Enhanced SIT and diminished VIP levels are found in rats following misoprostol treatment. It appears that inhibited VIP release is one of the mechanisms in misoprostol-enhanced SIT.     

Three-dimensional high-resolution anorectal manometry: A comparative pilot study with X-ray defaecography

Three-dimensional high-resolution anorectal manometry (3DHRAM) is a new technique that can explore anorectal disorders and provide interesting topographic data for the diagnosis of pelvic floor disorders such as paradoxical puborectalis syndrome (PPS). Our object was to evaluate whether 3DHRAM can reliably diagnose PPS already diagnosed with X-ray defaecography, which is considered to be the gold standard.All patients being tested in our department for dyschezia by 3D-HRAM and X-ray defecography were eligible for the study. The 3DHRAM results were compared with X-ray defecography. The sensitivity, specificity, and positive and negative predictive values were calculated for various 3DHRAM criteria to propose a diagnostic strategy for PPS.Twenty-three patients presented with PPS on X-ray defaecography. On 3DHRAM, according to our diagnostic strategy, the kappa value was 0.706, with a positive predictive value of 71.88% [95% CI, 53.02–85.60], a specificity of 80.43% [95% CI, 65.62–90.13], a sensibility of 95.83% [95% CI, 76.98–99.78], and area under curve value was 0.922.In this study, 3DHRAM was used to diagnose PPS with the same degree of reliability as X-ray defaecography, and we confirmed its use in the diagnosis of pelvic floor disorders. Further studies will be necessary to define classifications for these new anatomic data from 3DHRAM.     

Gastrointestinal transit through esophagus,stomach, small and large intestine in patients with progressive systemic sclerosis

Liquid esophageal transit and gastric emptying, mouth-to-cecum transit, and whole gut transit of a solid-liquid meal were measured in 14 patients with PSS, 16 control subjects (esophageal transit), and 20 control subjects (gastrointestinal transit), respectively, by using scintigraphic techniques, the hydrogen breath test, and stool markers. In patients with PSS, the glucose hydrogen breath test for detection of small intestinal overgrowth was performed and various gastrointestinal symptoms were determined. Esophageal transit and gastric emptying were significantly prolonged in PSS patients with 11 of 14 PSS patients (79%) disclosing delayed esophageal transit and eight of 14 PSS patients (57%) disclosing delayed gastric emptying. All PSS patients with prolonged gastric emptying also had delayed esophageal transit and there was a significant positive correlation between esophageal transit and gastric emptying (r=0.696,P<0.01). No significant differences between PSS patients and controls were detected concerning mouth-to-cecum transit and whole gut transit, but abnormally delayed mouth-to-cecum transit was found in four of 10 PSS patients (40%) and abnormally prolonged whole gut transit was detected in three of 13 PSS patients (23%). Small bacterial overgrowth was diagnosed in three of 14 PSS patients (21%). Delayed esophageal transit and gastric emptying were associated with dysphagia, retrosternal pain, and epigastric fullness, while prolonged whole gut transit was associated with constipation. It is concluded that delayed gastric emptying is frequently associated with esophageal transit disorders in PSS patients and may be one important factor for the development of gastroesophageal reflux disease in these patients.     

Reproducibility of colonic transit study in patients with chronic constipation

PURPOSE: Major therapeutic decisions are rendered based on a single colonic transit study. Therefore, the aim of this study was to assess the reproducibility of colonic transit time in patients with chronic constipation. MATERIALS AND METHODS: Fifty-one patients with chronic idiopathic constipation were randomly selected to undergo two separate colonic transit tests. All clinical conditions, methodology, and patients' instructions were identical on both occasions. The gamma rate (linear correlation analysis) was undertaken between the first and second colonic transit times. Groups were divided according to the diagnoses of colonic inertia (slow-transit constipation), paradoxical puborectalis contraction, and chronic idiopathic constipation (normal-transit constipation). RESULTS: In 35 of 51 patients (69 percent), the results were identical between the two studies; however, in 16 patients (31 percent), the results were disparate (gamma correlation coefficient =0.53;P<0.01). The specific correlation coefficients for patients with colonic inertia, paradoxical puborectalis contraction, and chronic idiopathic constipation were 0.12, 0.21, and 0.60 (P<0.01), respectively. Moreover, the success rate of colectomy for colonic inertia was significantly higher in patients who underwent a repeat transit study confirming inertia than in patients who underwent colectomy based on a single study. CONCLUSIONS: Overall, colonic transit time is reproducible in patients with chronic constipation. The correlation coefficient is best for patients with idiopathic constipation and worst for patients with colonic inertia. This new finding suggests that suboptimal surgical outcome may be attributable to inaccurate diagnosis. Because of this poor correlation coefficient, in patients with colonic inertia, consideration should be given to repeating the colonic transit study before colectomy to help secure the diagnosis and improve outcome.This study was sponsored in part by a generous educational grant from the Caporella family.Read at The American Society of Colon and Rectal Surgeons' 100th Anniversary and Tripartite Meeting, Washington, D.C., May 1 to 6, 1999.     

Colonic substance P levels are increased in ulcerative colitis and decreased in chronic severe constipation

Substance P content was determined by radioimmunoassay in colonic mucosa from 24 patients with chronic severe constipation, 16 with active ulcerative colitis, and 28 normal controls. In patients with chronic severe constipation, the mean concentration of substance P (19.9±8.2 pg/mg) was significantly lower than in normal subjects (71±18 pg/mg). In patients with ulcerative colitis, colonic substance P concentration in inflamed mucosa (170±46 pg/mg) was significantly higher than its levels in normal subjects. Substance P may therefore have a role in the pathogenesis of clinical conditions associated with diarrhea and constipation.     

Distribution of vasoactive intestinal polypeptide and substance P receptors in human colon and small intestine

Vasoactive intestinal polypeptide (VIP) and substance P are found in neurons in the lamina propria and submucosa and muscularis propria of human small intestine and colon. VIP receptors coupled to adenylate cyclase are present on epithelial, smooth muscle, and mononuclear cells. This study analyzes the distribution of[¹²⁵I]VIP binding and [¹²⁵]substance P in human colon and small intestine using autoradiographic techniques. [¹²⁵I]VIP binding was present in high density in the mucosal layer of colon and small intestine. [¹²⁵I]VIP binding was not significantly greater than nonspecific binding in smooth muscle layers or the lymphoid follicles. In contrast, [¹²⁵I]substance P binding was present in high density over the colonic muscle but was not present over the mucosal layer. In human colon cancer, [¹²⁵I]VIP grain density over the malignant tissue was only slightly higher than background. These autoradiographic studies of [¹²⁵I]VIP binding indicate that the highest density of VIP receptors was found in the small intestine and superficial colonic mucosa, whereas the density of substance P receptors was highest over the smooth muscle layers. These findings suggest a mismatch between immunochemical content of the peptide and autoradiographic density of the receptor.This work was supported by funds from the Research Service of the Veterans Administration.