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Postprandial Duodenal Function in Man' Gut: first published as 10.1136/gut.19.8.699 on 1 August 1978. Downloaded from Gut, 1978, 19, 699-706 Postprandial duodenal function in man' L. J. MILLER,2 J.-R. MALAGELADA, AND V. L. W. GO3 From the Gastroenterology Unit, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA SummARY Duodenal function was studied in 11 healthy volunteers after intragastric instillation of a mixed semi-elemental meal. The duodenum accepted chyme of varying pH, osmolality, and nutrient concentration; and, as a result of biliary, pancreatic, and enteric secretion as well as absorption, it delivered chyme with nearly constant pH, osmolality, and nutrient concentration to thejejunum. The flow rate and nutrient load ofjejunal chyme varied. The duodenum absorbed more carbohydrate than lipid and less protein, taking up each nutrient at a constant rate during most of the postprandial period. The percentage of nutrient load absorbed was greatest in the late postprandial period, when flow rate, nutrient load, and concentrations were low. Duodenal chyme influences all major functions of the substances and changes and of the nutrient absorp- duodenum; yet postprandial chyme in normal man tion taking place at this level of the bowel after has not been fully characterised. Duodenal hormonal ingestion of a liquid, mixed, semi-elemental meal. and neural regulation of gastric, pancreatic, and Although this meal might not induce the same duo- biliary secretion and of upper gastrointestinal motor denal events as a more complex one, it was used to activity is sensitive to chyme nutrient content simplify analytical procedures. (Windsor et al., 1969), osmolality (Meeroff et al., 1975), and pH (Johnston and Duthie, 1966). Methods Pancreatic and biliary secretions that are important http://gut.bmj.com/ to digestion mix with chyme in this segment of bowel SUBJECTS and are similarly sensitive to the characteristics of Eleven healthy volunteers (two female and nine chyme. An example of this is seen in the Zollinger- male, aged 21 to 62 years) participated in 16 studies Ellison syndrome, where duodenal delivery of an after giving informed consent. All data reported as acidic chyme inactivates lipase and precipitates bile results are from the initial study performed in each acids, thus producing steatorrhoca (Go et al., 1970). of the 11 subjects. The five duplicate studies are Also, duodenal absorption and secretion of fluid and used only to provide further independent assessment electrolytcs and absorption of nutrients are certainly of the correlation between emptying of nutrient and on September 28, 2021 by guest. Protected copyright. dependent on the composition of duodenal chyme. of meal marker in a particular study. This is apparent in considering the dumping syn- drome (Abbott et al., 1960). MEAL Little information has been obtained from normal A 400-mI standard liquid meal containing about 300 man to characterise the postprandial gastric contents calories distributed as 40 % carbohydrate, 40 % lipid, delivered into the duodenum, the modifications of and 20% protein (similar to their distribution in the this chyme that occur along the duodenum, and the normal American diet) was used. The nutrients were chyme that is delivered into the jejunum. We have semi-elemental, in forms normally appearing in the tried to develop more thorough knowledge of these bowel lumen, which could be assimilated easily and which permitted simple analysis of intestinal chyme for nutrient composition. The meal was prepared by 'Supported in part by Research Grant AM-6908 from the dissolving in water 30 7 g maltose (0-224 molar), 14 g National Institutes of Health, Public Health Service. oleic of a 'Dr Laurence Miller is an NIH trainee supported by Grant acid (0-124 molar), l 64 g complete tryptic AM-7198 from the National Institutes of Health, Public hydrolysate of casein, and 15 g of a nonabsorbable Health Service. marker (polyethylene glycol 4000) and adjusting the 'Address for reprint requests: Dr V. L. W. Go, Gastro- pH to 7 0 with a small amount of NaOH. Sonication enterology Unit, Mayo Clinic, Rochester, Minnesota 55901, for 10 minutes produced an emulsion with osmola- USA. lity 544 ± 5 mOsm/l which was stable for several Received for publication 6 January 1978 hours, thus longer than the study period. 699 Gut: first published as 10.1136/gut.19.8.699 on 1 August 1978. Downloaded from 700 L. J. Miller, J.-R. Malagelada, and V. L. W. Go TUBES than 92 % of marker was recovered proximal to the Two peroral tubes were used (Fig. 1). For the duo- balloon in all studies. No study was included in denum, there was a sump tube that ran to a mercury- which duodenal-gastric reflux of duodenal marker weighted tip beyond an occlusive balloon and had exceeded 15 %. three small polyvinyl tubes cemented to it. This Fasting gastric and duodenal collections were made assembly (of total external diameter, except for the by continuous suction (- 25 mm Hg) during two 10- balloon, of approximately 6 mm) provided (1) the minute intervals. duodenal perfusion site; (2) an aspiration site with an Then the meal was injected via the gastric tube over air channel, to facilitate suction, located 20 cm distal eight minutes, and gastric and duodenal samples to the perfusion site; (3) an inflatable balloon were collected for two hours after the meal. Every 10 immediately distal to the aspiration site; and (4) an minutes, 200 ml of gastric contents was aspirated, a aspiration site immediately beyond the balloon. 10-ml aliquot was taken from it, and the remainder Gastric sampling was done via a separate 14-F sump was returned immediately to the stomach. The tube. aliquots from each 30-minute interval were pooled. Duodenal samples were aspirated by continuous PROCEDURE suction (-25 mm Hg), collected over ice, and pooled Each study was begun after an overnight fast. The at 30-minute intervals. No duodenal chyme was volunteers were seated in an upright position through- reinfused. To correct for transit time, duodenal col- out the study. Under fluoroscopic control, the duo- lections were begun five minutes after corresponding denal tube was positioned with the balloon at the gastric collections. ligament ofTreitz and the gastric tube was positioned At the end of the study period, gastric contents with its tip in the most dependent area ofthe antrum. were aspirated completely; then 200 ml of a normal Duodenal perfusion with 14C-PEG (polyethylene saline gastric wash was injected over five minutes; glycol, specific activity 0 5 zCi/mg) dissolved in 0-15 and this was aspirated, to recover as much of the M NaCl was maintained at 2 ml/min throughout the marker as possible. study period. The occlusive balloon was inflated with Determinations of osmolality (Wescor 5100 Vapor 30 to 45 ml ofair until the subject sensed its presence, Pressure Osmometer) and pH (Fisher 520 Digital without having any discomfort. Total occlusion was pH/Ion Meter) were performed immediately on all confirmed by demonstrating that neither bile nor gastric and duodenal samples. Marker concentrations http://gut.bmj.com/ 14C-PEG was present distal to the balloon. More also were measured in all samples (Brunner et al., tleal (+PEG) on September 28, 2021 by guest. Protected copyright. Fig. 1 Peroralgastric sump tube and riC sampling multiluminalduodenalassembly, as placedfor use. Duodenal ( Q -' 77 Ai perfusion uode (+ '4C-PEG, al aspiration 2 ml/min) O1cclusive balloon -Sampling site distal to balloon Gut: first published as 10.1136/gut.19.8.699 on 1 August 1978. Downloaded from Postprandial duodenalfunction in man 701 1974), and bilirubin and trypsin concentrations were stable, however, close to neutrality (Fig. 2). Osmo- measured in all duodenal samples (Brunner et al., lality of the chyme behaved similarly: after the meal 1974). Bilirubin and trypsin outputs as well as the (osmolality 544), gastric osmolality progressively gastric volume emptied and meal emptied were decreased toward the osmolality of blood (each point calculated as previously reported (Brunner et al., different from preceding point, P < 0-01). This steady 1974; Malagelada et al., 1976). The formulas were decline of the osmolality of gastric contents entering modified to include the actual volume collected at the the duodenum was not reflected by chyme at the ligament of Treitz rather than a flow rate previously ligament of Treitz, where osmolality remained stable calculated from the duodenal perfusate (Malagelada near isotonicity (Fig. 2). et al., 1976; Clain et al., 1977). Therefore, charac- terisation of gastric contents emptied into the duo- denum was indirect (based on marker determina- Meal tions), and that of chyme leaving the duodenum was 8 Chyme at ligament of Treitz measured directly. 7 'W Total protein was determined by the method of 6 Lowry et al. (1951), fatty acid by the method of Z 5 Cohen et al. (1969), carbohydrate by analysis of Q 4 Gastric contents maltose (Bernfeld, 1955), and glucose by the hexo- 3 entering duodenum kinase method (Bergmeyer et al., 1974). In the mal- 2 l tose assay, correction was made for free glucose I I I present. Nutrient assays were performed on the meal, 600 all duodenal samples, and the gastric contents aspirated at the end of the two-hour study period. \ 500 Although we cannot be sure that we were measuring Gastric contents only exogenous nutrient, the contribution by endo- 400 enering duodenum genous secretions probably was very small. E 3; 300 .__ _ --__________ VALIDATION STUDY Chyme at ligament of Treitz In an attempt to determine the maximal potential 200 C) http://gut.bmj.com/ interference, a validation study was performed in 100 I Mean whichpancreaticandbiliary secretionsaspirated from ± SE 90 l I five normal subjects at the time of maximal chole- 120 cystokinin stimulation were analysed for carbo- 0 30 60 90 hydrate, lipid, and protein by the same techniques Time postprandial, min mentioned above.
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