Effect of intestinal resection on human small bowel motility.

BACKGROUND: Few data are available on adaptive changes of human small bowel motility after intestinal resection. AIM: To characterise jejunal motility after extensive and limited distal intestinal resection. METHODS: Seven patients with a short bowel syndrome after total ileal and partial jejunal resection (residual jejunal segments between 60 and 100 cm) and six patients with limited distal ileal resection (resected segment between 30 and 70 cm) underwent ambulatory 24 hour jejunal manometry 15 (6-24) months after the operation. Normal values were obtained from 50 healthy subjects. Fasting motility and the motor response to a 600 kcal solid meal were analysed visually and by a computer program. RESULTS: Limited ileal resection did not result in changed jejunal motility. After extensive distal resection, patients had a significantly shorter migrating motor complex (MMC) cycle and a significantly shorter duration of the postprandial motor response compared with controls (p < 0.005). Intestinal resection had no influence on jejunal contraction frequency and amplitude and did not lead to any abnormal motor pattern. CONCLUSION: Extensive distal resection of the small intestine produces distinct abnormalities of fasting and postprandial motility in the intestinal remnant. The shortening of digestive motility and the increased frequency of MMC cycling could contribute to malabsorption and diarrhoea in the short bowel syndrome.     

Changes in motility after jejunal and ileal resection: electromyographic study in rats

The aim of this work was to compare the effects of massive jejunal and ileal resections on intestinal motility using an electromyographic technique. Male Wistar rats were used: in the first group a massive jejunal resection was performed, conserving a 7-cm segment after the ligament of Treitz; the rats of the second group underwent an ileal resection, preserving 7 cm of the terminal ileum. Motility was studied at the 10th and 30th postoperative days by means of electrodes implanted throughout the remaining bowel and was expressed by the pattern of recurrence of the migrating myoelectric complex (MMC). In a fasting state, in both transected and resected animals at the 10th postoperative day, the gradient in the duration of MMC along the intestine still existed. However, on the 30th postoperative day, in animals with jejunal resection only, there was an adaptive process: the duration of MMC in the remaining jejunum was significantly increased to the duration in the ileum. After the end of the postprandial inhibition of the appearance of the MMC, on the 10th postoperative day there was a significant decrease in the duration of MMC in the ileum in both types of resection, compared to the controls. However, on the 30th postoperative day, the duration of MMC returned to its control value. In conclusion, jejunal resection seems to induce more important adaptive processes in intestinal motility than does ileal resection. The different results are discussed.     

Cyclic motor activity and trophicity after jejunal resection and bypass in rats

The aim of the study was to examine the changes in intestinal motility induced by an extensive jejunal resection and bypass in rats using an electromyographic technique. The relationship, if any, between the development of motility and adaptive modifications of intestinal trophicity was also studied. A massive jejunal resection, preserving a 7-cm segment distal to the ligament of Treitz, was performed in one group of animals. In a second group, the jejunum was bypassed as a self-emptying blind loop. Two sham-operated groups underwent transection and reanastomosis on the proximal jejunum or ileum. Electromyographic activity was studied at the 10th and 30th postoperative days by means of electrodes implanted throughout the remaining or bypassed bowel and was expressed by means of the pattern of recurrence of the migrating myoelectric complex (MMC). After a month, the animals were sacrificed. Mucosal and muscular wet weight and protein content (mg/cm) of the intestine were then determined. The results showed that 10 days after the jejunal resection in the fasting state, MMC cycle duration is different in the remaining jejunum and in the ileum. However, the distribution of MMC phases in the jejunum was modified and was similar to the one in the ileum. Thirty days after resection, MMC cycle duration, as well as phase distribution in the remaining jejunum, resemble the MMC patterns in the ileum. These changes were not observed after bypass. After the return of MMCs after postprandial inhibition produced by a meal, MMC duration in the ileum was greatly decreased until a month after jejunal resection. In contrast, the jejunal bypass did not produce this modification.     

Variability of motility of the ileum and jejunum in healthy humans

Motor patterns of the distal small bowel were defined in healthy humans, using a multilumen polyvinyl tube, passed by mouth in 11 healthy subjects. Five recording sites, spanning 100 cm of tube and featuring a nitrogen hydraulic infusion system, were used to obtain records during 6 h of fasting and 6 or more hours after ingestion of a 600-kcal liquid test meal. The loci of recordings were designated as jejunal, ileal, or terminal ileal, as judged by the length of tube within the intestine and by fluoroscopy. During fasting, the migrating motor complex was present in all subjects and at all levels of the small intestine, but it could not be traced into the colon. Interdigestive cycles were defined primarily by the presence of an "activity front" (phase 3 of the migrating motor complex). Ninety-six migrating motor complexes occurred each 97 min (grand mean for all loci), but intervals between individual activity fronts varied markedly (15-195 min), in contrast to what is reported in other species. The velocity of aboral migration was 4.7 +/- 1.8, 1.3 +/- 0.4, and 0.9 +/- 0.2 cm . min-1 (mean +/- SD) in jejunal, ileal, and terminal ileal, respectively. Rates of continuous, rhythmic contractions during activity fronts declined distally: 12.5 to 10.5 (jejunal), 10.9 to 9.3 (ileal), and 10.0 to 8.6 cycle/min (terminal ileal), respectively. In individual subjects, maximum rates of contraction and velocities of migration always declined distally, but the duration of activity fronts was unrelated to the level of recording. Food interrupted the fasting cycles of motility for periods ranging from 2.75 to greater than 10 h. The transition from the fasting to the fed pattern was prompt and the postprandial motility was that of irregular bursts of contractions interspersed with transient quiescence. These studied demonstrate that the migrating motor complex occurs throughout the human small intestine, and that inter- and intraindividual variations are marked; food disrupts the complex for variable periods. These variations must be considered when abnormalities are being sought in disease states.     

Effect of parenteral nutrition supplemented with short-chain fatty acids on adaptation to massive small bowel resection

After massive small bowel resection, total parenteral nutrition (TPN) is prescribed to maintain nutritional status. However, TPN reduces the mass of the remaining intestinal mucosa, whereas adaptation to small bowel resection is associated with increased mucosal mass. Short-chain fatty acids (SCFAs) have been shown to stimulate mucosal cell mitotic activity. This study determined whether the addition of SCFAs to TPN following small bowel resection would prevent intestinal mucosal atrophy produced by TPN. Adult rats underwent an 80% small bowel resection and then received either standard TPN or TPN supplemented with SCFAs (sodium acetate, propionate, and butyrate). After 1 wk, jejunal and ileal mucosal weights, deoxyribonucleic acid, ribonucleic acid, and protein contents were measured and compared with the parameters obtained at the time of resection. Animals receiving TPN showed significant loss of jejunal mucosal weight, deoxyribonucleic acid, ribonucleic acid, and protein and ileal mucosal weight and deoxyribonucleic acid after small bowel resection, whereas animals receiving SCFA-supplemented TPN showed no significant change in the jejunal mucosal parameters and a significant increase in ileal mucosal protein. These data demonstrate that SCFA-supplemented TPN reduces the mucosal atrophy associated with TPN after massive bowel resection and thys may facilitate adaptation to small bowel resection.     

Mucosal Growth and Enzyme Activity during the Early Phase of Adaptation after Jejunal Bypass in the Rat

Morphological variables and mucosal enzyme activities were measured in the bypassed and remaining parts of the small intestine 3, 7, and 14 days after a jejunal bypass operation. In the bypassed segment tissue mass, enzyme activity per unit intestinal length, and enzyme activity per unit DNA were gradually reduced. In sham-operated animals tissue mass increased, whereas enzyme activity per unit DNA was reduced. In the segment remaining in function, tissue mass increased, whereas enzyme activities decreased temporarily. In this part of the intestine, the changes were more or less parallel in bypassed and sham-operated animals. It may be concluded that the enzymatic changes are not correlated to the morphologic changes in the early phase of adaptation to intestinal bypass.     

Sandostatin impairs postresection intestinal adaptation in a rat model of short bowel syndrome

Because of its antisecretory properties, sandostatin has been advocated for the treatment of patients with short bowel syndrome (SBS). This study was conducted to determine the effect of sandostatin on structural intestinal adaptation, cell proliferation and apoptosis in a rat model of SBS. Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection, SBS rats underwent 75% small bowel resection, and SBS-sandostatin rats underwent bowel resection and were treated with sandostatin (SBS-SND). Parameters of intestinal adaptation, enterocyte proliferation, and enterocyte apoptosis were determined on day 14 following operation. We have demonstrated that SBS-SND animals demonstrated lower (vs SBS rats) duodenal and jejunal bowel weights, jejunal and ileal mucosal weight, jejunal and ileal mucosal DNA and protein, jejunal and ileal villus height, cell proliferation index in the ileum, and enterocyte apoptosis in jejunum and ileum. We conclude that in a rat model of SBS sandostatin decreases cell proliferation and inhibits structural intestinal adaptation.     

Long-duration stress

No extensive information exists in literature concerning the late or residual effects of stress on motility of small bowel and colon. Moreover, the duration and magnitude of the intestinal motor response to stress are still ignored. Therefore, the aim of our work was to determine, in rat, the effect of long-duration stress induced by restraint on the motility of small bowel and colon. Observations were made during physical restraint and 60 h later. Bipolar electrodes were implanted on the gastrointestinal serosa from the pylorus to the sigmoid colon in male Wistar rats. Electromyographic (EMG) recordings were made during fasting state, and a control EMG recording session was performed during 12 hr, followed by a 12-hr recording during restraint stress. After a 60-hr resting period, another EMG recording session was performed during 3 hr. During stress in the pylorus and small bowel, the recurrence of migrating myoelectrical complexes (MMCs) was immediately interrupted and replaced by a continuous and irregular activity. The motility index (number of spike bursts/10 min) was augmented rapidly on the jejunum and ileum, but it increased only gradually on the pylorus. Only on the transverse colon were the number of spike bursts/hour and their relative duration increased after 7 hr of physical restraint. In contrast, the sigmoid colon displayed a gradual decrease in the relative duration of contractile activity during the first 6–7 hr of stress. At 60 hr after stress in the pylorus and small bowel, a normal control motor activity was restored (MMC, motility index) on the jejunum and on the ileum, but the motility index on the pylorus was decreased. Throughout the colon, a faster motor activity as well as an increase in the number of spike bursts/hour was observed. In conclusion, a 12hr physical restraint stress induced instant drastic changes in small bowel motility, but a normal motility pattern was rapidly restored after the end of the stress period. However, on the colon, the motor changes are moderate at the beginning of the restraint period, then gradually increased with time, and were still largely persistent three days after the cessation of physical restraint.     

Effects of decreasing intraluminal amylase activity on starch digestion and postprandial gastrointestinal function in humans

We used an amylase inhibitor preparation that markedly improves postprandial carbohydrate tolerance in humans to investigate the effects of decreased intraluminal amylase activity on digestion of starch and postprandial gastrointestinal and hormonal responses. Four fasting volunteers were intubated with an oroileal tube to obtain duodenal, jejunal, and terminal ileal samples. After intubation, subjects ingested 50 g of rice starch given with placebo; on the second day, starch was given with the amylase inhibitor. Compared with placebo, the amylase inhibitor significantly (p less than 0.05) reduced duodenal, jejunal, and ileal intraluminal amylase activity by more than 95% for 1-2 h; increased postprandial delivery of total carbohydrate (glucose polymers in particular) to the distal small bowel; increased breath hydrogen concentrations; decreased intestinal water absorption and increased distal intestinal volume delivery to the distal bowel; shortened duodenoileal transit time but doubled postprandial gastric emptying time; reduced the early postprandial plasma glucose rise by 85% and eliminated the late postprandial glucose fall to below fasting levels; and abolished postprandial plasma concentrations of insulin, C-peptide, and gastric inhibitory polypeptide. Postprandial trypsin output was not influenced. We conclude that more than 95% inhibition of amylase reduces dietary starch digestion within the small intestine and uptake of dietary starch from the small intestine, markedly decreases postprandial release of insulin and gastric inhibitory polypeptide, and may alter postprandial upper gastrointestinal motor function.     

Effects of enteral arginine supplementation on the structural intestinal adaptation in a rat model of short bowel syndrome

The nitric oxide precursor L-arginine (ARG) has been shown to influence intestinal morphology and intestinal absorptive function. The purpose of the present study was to determine the effect of enteral ARG supplementation on structural intestinal adaptation, cell proliferation, and apoptosis in a rat model of short bowel syndrome (SBS). Thirty male Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection, SBS rats underwent 75% small bowel resection, and SBS-ARG rats underwent bowel resection and were treated with ARG given in the drinking water (2%). Parameters of intestinal adaptation, enterocyte proliferation and enterocyte apoptosis were determined on day 14 following operation. We have demonstrated that SBS-ARG animals had a lower jejunal and ileal mucosal weight, jejunal mucosal DNA and protein, ileal mucosal protein, jejunal villus height, jejunal and ileal crypt depth, and enterocyte proliferation index and a greater enterocyte apoptosis compared to SBS untreated animals. We conclude that in a rat model of SBS enteral L-arginine inhibits structural intestinal adaptation. Possible mechanism for this effect may be decreased cell proliferation and increased cell apoptosis.     

Increased activity of digestive enzymes in ileal enterocytes adapting to proximal small bowel resection.

The ability of adapting ileal enterocytes to express different digestive enzymes in their brush border membranes was tested in young female Wistar rats (n = 72) receiving 60% proximal small bowel resection. In control rats with intestinal transection both neutral aminopeptidase and alpha-glucosidase activities were shown, by quantitative cytochemistry, to increase during enterocyte migration over the lower part of the villus; thereafter enzyme activities declined or remained approximately constant. Proximal enterectomy increased the amount of alpha-glucosidase but not neutral aminopeptidase activity appearing during early enterocyte development. Thymidine labelled autoradiography showed that the rate of enterocyte migration along the ileal villus nearly doubled after jejunal resection (19.3 v 11.1 microns/h). Nevertheless, the time taken for both peptidase and saccharidase activities to appear at maximal rates in the brush border membrane was diminished by about five hours. Thus ileal enterocytes adapt to proximal small bowel resection by selective increments in enzyme expression, findings that contradict the previous hypothesis of simple metabolic immaturity.     

The effect of resection of the jejunum and ileum on intestinal mucosal trophism. An experimental study on the rat]

Intestinal resection leads to anatomo-physiological adaptive changes in the small bowel depending on its localization and extension. Two 50% resection models were done, jejunal resection (55 cm.) and ileal resection (55 cm.), in the attempt to determine the trophic response of the remnant bowel from jejunal and ileal samples. Significant increases were seen in mucosal villous length, jejunal values were greater than ileal and the greatest values were when the whole ileum was conserved. No significant changes were observed in DNA contents. These data suggest the importance of the ileal segment in the intestinal adaptive process, especially on the jejunal segment, as well as the apparent end of this response two weeks after resection.     

Time course of adaptive regulatory peptide changes following massive small bowel resection in the dog

Basal and postprandial concentrations of gastrointestinal hormones were measured in 12 dogs before and at one and three months after a 75% small bowel resection. Five animals were studied again at six months. Concentrations of enteric hormones and neuropeptides, measured in the proximal jejunum and distal ileum adjacent to the anastomotic site at the time of euthanasia, were compared with concentrations in control tissues taken from each animal at the time of resection. Increased basal and postprandial levels of gastrin (P<0.05), cholecystokinin (CCK,P<0.05), glucose-dependent insulinotropic peptide (GIP,P<0.01), peptide YY (PYY,P<0.001), and enteroglucagon (P<0.001), were seen at one month after small bowel resection. In contrast, no significant changes were seen in concentrations of secretin, motilin, neurotensin, somatostatin, PP, or glucagon. Concentrations of enteroglucagon, GIP, and PYY remained high throughout the six-month study period. In contrast, gastrin and CCK had normalized by three months. Thus, only enteroglucagon, PYY, and GIP showed sustained elevations following enterectomy; the gastrin and CCK changes were transient. Following enterectomy, concentrations of vasoactive intestinal polypeptide (VIP) were reduced by about 50% in mucosal (P<0.001) and muscle (P<0.05) layers of proximal and distal gut. In contrast, calcitonin gene-related peptide (CGRP) was increased by about twofold in jejunal and ileal mucosa (P<0.05), and CGRP elevations were even more marked in the muscle layers (P<0.001). Somatostatin and neuropeptide Y (NPY) concentrations were similar to controls in all areas except for a small decrease in NPY in ileal mucosa (P<0.05). These findings suggest that the increased motilin and PP concentrations previously reported after bowel resection in man are more likely to reflect underlying inflammatory bowel disease rather than enterectomy. The normalization of hypergastrinemia explains why the increased acid secretion after small bowel resection is transient. These results provide evidence for independent secretory control of enteroglucagon and PYY, which are both products of intestinal L cells. In addition, these studies reveal marked changes in enteric neuropeptide concentrations following bowel resection. VIP, which is thought to be a major inhibitory transmitter in the gut, is markedly reduced, while CGRP, which is mainly localized in sensory afferent fibers, is increased. These major neuropeptide changes are likely to be of importance in the adaptive responses to massive small bowel resection.Presented at the annual Meeting of the American Gastroenterological Association in Boston, May 1993, and published in abstract form inGastroenterolgy 104:A232 and A468, 1993.     

Intestinal regrowth is amplified after jejunal but not ileal resection during tapeworm infection in the rat

The ileum possesses functions required by a healthy individual that are not fully supplanted by the duodenum or jejunum. Evidence suggests that the ileum may also be necessary to maintain an enteric parasite–host interaction. We hypothesized that the ileum is essential to the survival of the lumen-dwelling, rat tapeworm, H. diminuta. Male rats were divided into three groups: those with ileal or jejunal resections and nonresected controls. Half of each rat group was infected with the tapeworm. After jejunal resection, the weight but not length of intestinal remnant (duodenum + ileum) in infected rats returned to that of control, nonresected intestine 29 days after surgery and tapeworm numbers were fully maintained. In contrast, after ileal removal intestinal length and weight of the remaining duodenum and jejunum in infected rats were significantly decreased and tapeworm survival diminished. Data indicates that intestinal growth following resection is amplified by tapeworm infection when the ileum remains but diminished when the ileum is removed. Furthermore, loss of the ileum results in decreased infection intensity and dry weight of the tapeworm.     

Intestinal Growth Adaptation and Glucagon-like Peptide 2 in Rats with Ileal–Jejunal Transposition or Small Bowel Resection

Glucagon-like peptide 2 (GLP-2), produced by enteroendocrine L-cells, regulates intestinal growth. This study investigates circulating and intestinal GLP-2 levels in conditions with altered L-cell exposure to nutrients. Rats were allocated to the following experimental groups: ileal–jejunal transposition, resection of the proximal or distal half of the small intestine, and appropriate sham-operated controls. After two weeks, ileal–jejunal transposition led to pronounced growth of the transposed segment and also of the remaining intestinal segments. Plasma GLP-2 levels increased twofold, whereas GLP-2 levels in the intestinal segments were unchanged. In resected rats with reduced intestinal capacity, adaptive small bowel growth was more pronounced following proximal resection than distal small bowel resection. Circulating GLP-2 levels increased threefold in proximally resected animals, and twofold in the distally resected group. Tissue GLP-2 levels were unchanged in resected rats. The data indicate that transposition of a distal part of the small intestine, and thereby exposure of L cells to a more nutrient-rich chyme, leads to intestinal growth. The adaptive intestinal growth is associated with increased plasma levels of GLP-2, and GLP-2 seems to act in an endocrine as well as a paracrine manner.     

Effect of pacing on small intestinal motor activity and hormonal response in dogs

In seven beagle dogs with a Thiry-Vella loop, the effect of pacing on small intestinal motor activity was examined by means of extraluminal strain gauge force transducers. Recordings were obtained from the loop and from the remaining small intestine. Our study showed that pacing of the loop results in a significant reduction of the motility of the loop in the overnight fasted state (up to 39%), during loop feeding (up to 55%), and oral feeding (up to 39%); a similar reduction of the motility of the remaining small intestine (up to 43%); and a significant postprandial increase of insulin (9.0 U/ml) and decrease of glucagon (94 pg/ml). The motility reduction of the loop and of the remaining small intestine as well as the anabolically improved pancreatic endocrine function (shown by an increase of the insulin — glucagon ratio) suggests that this form of pacing could be of benefit for motility disorders with decreased transit time.The present study was supported by Deutsche Forschungsgemeinschaft.     

Jejunal brake

Optimal absorption of fat requires adequate time of contact with the absorptive sites of the small intestine. In order to prevent steatorrhea, intestinal transit must be slowed in response to the fat that has emptied into the small intestine. Intestinal transit is known to be inhibited by fat in the ileum via the ileal brake. This response has suggested that the regulation of intestinal transit is a function of the distal small intestine. However, clinical observations suggest that the ileal brake is not the only control mechanism for intestinal transit. In short bowel patients with resection of the ileum, the proportion of fecal fat recovery remained constant even after the fat intake was increased threefold. In these patients, optimal fat absorption based on the slowing of intestinal transit must have been triggered by an inhibitory mechanism located outside of the distal small intestine. To test the hypothesis that fat in the proximal small intestine inhibited intestinal transit, we compared intestinal transit during perfusion of the proximal half of the small intestine with 0 (buffer only), 15, 30, or 60 mM oleate in dogs equipped with duodenal and mid-intestinal fistula. Intestinal transit across a 150-cm test segment (between fistulas) was measured by counting for the recovery of a radioactive marker in the output of the mid-intestinal fistula during the last 30 min of a 90-min perfusion. We found that oleate inhibited intestinal transit in a load-dependent fashion (P<0.005). Specifically, while the mean cumulative recovery of the transit marker was 95.5% during buffer perfusion, the recovery decreased when 15 mM (64.3%), 30 mM (54.7%), or 60 mM oleate (38.7%) was perfused into the proximal half of the small intestine. We conclude that fat in the proximal small intestine inhibits intestinal transit as the jejunal brake.     

Effect of age on human gastric and small bowel motility

To test the hypothesis that age alters fasting and postprandial antral and intestinal motility in humans, we studied 23 patients, aged 18-39 years (median 28), and 13 patients, aged 40-69 years (median 49). All were having gastrointestinal symptoms, but in none was there objective clinical, radiologic, or endoscopic features of bowel disease, and manometry of the stomach and proximal small bowel was normal. We quantitated certain parameters of fasting intestinal motility and postprandial antral and jejunal motility. There were no significant differences in the interval between interdigestive motor complexes (IMC), duration, propagation velocity, or maximum number of contractions during phase III of the IMC, or postprandial antral and jejunal motility indices. The postprandial indices show a very similar distribution in each decade. Thus, in selected patients with unexplained gastrointestinal symptoms but no objective features of gut disease, quantifiable gastric and small bowel motility parameters do not differ in the age groups 18-39 and 40-69 years.     

Oral Insulin Enhances Intestinal Regrowth Following Massive Small Bowel Resection in Rat

Experimental studies have suggested that insulin (INS) plays an important role in small intestinal growth and development. In the present study we investigated the effect of oral INS on structural intestinal adaptation and enterocyte proliferation and loss via apoptosis in a rat model of short bowel syndrome (SBS). Male Sprague–Dawley rats were divided into three experimental groups: sham rats underwent bowel transection, SBS rats underwent 75% small bowel resection, and SBS-INS rats underwent bowel resection and were treated with oral INS given in the drinking water from the 3rd to the 15th postoperative day. Parameters of intestinal adaptation (bowel and mucosal weight, mucosal DNA and protein, villous height, and crypt depth), enterocyte proliferation, and apoptosis were determined on day 15. SBS-INS rats demonstrated a significant increase (vs SBS rats) in jejunal and ileal overall bowel and mucosal weight, ileal mucosal DNA and protein, ileal villous height, and crypt depth. SBS-INS rats also showed an increased cell proliferation index in jejunum and ileum and decreased apoptotic index in jejunum compared to SBS animals. In conclusion, in a rat model of SBS, oral INS strongly enhances intestinal adaptation.Possible mechanisms may include increased cell proliferation and decreased enterocyte loss via apoptosis. Contributed equally to the preparation of this article.     

The value of in vivo electrophysiological measurements for monitoring functional adaptation after massive small bowel resection in the rat.

The process of functional adaptation after extensive small bowel resection is complex and imprecisely understood. In vivo electrophysiological measurements for monitoring the functional adaptive process after massive small bowel resection in Brown-Norway rats were evaluated. Rats underwent either a sham operation (SH) or a 90% small bowel resection (SB). Standard rat chow was fed in unlimited quantities. At three or 10 weeks after operation, jejunal and ileal transepithelial potential differences (PD, mV) were determined. Electrogenic ion transport in the villus was measured after glucose (sodium coupled active glucose absorption; PD-glu) and in the crypt, after theophylline infusion (theophylline stimulated chloride secretion; PD-theo). Biopsies were taken simultaneously. Each experimental group consisted of three to five animals. At three weeks the PD-theo and PD-glu in SB rats were significantly lower than in SH rats in both jejunal and ileal segments. At 10 weeks PD-theo and PD-glu were significantly diminished in the jejunal segment of the SB rats compared with the SH rats. The values of PD-theo and PD-glu in the ileal segments were, however, no longer different between the two groups. Three and 10 weeks after operation the length of the villi in the SB group was increased significantly compared with the SH controls. These results indicate that in the early phase of adaptation in vivo electrophysiological variables do not correlate with histological changes in the SB rats. This might be due to cell immaturity resulting from an increased rate of cell turnover or lack of intercellular tight junctions. This hypothesis is supported by a recovery of PD responses in the ileum 10 weeks after resection.