Gastric emptying of oil from solid and liquid meals

Digestion of fat in pancreatic insufficiency (PI) is strongly affected by how rapidly fat enters the duodenum. We postulated that: (1) oil empties faster in PI than in normals and (2) in both, it empties in a load-dependent fashion. We used a gamma camera to test these ideas by comparing gastric emptying of iodine-123 iodinated oil in normal and pancreatic-insufficient subjects after 15 g of free oil were ingested in a small spaghetti meal and 60 g of oil were ingested in a large spaghetti meal and in a milk emulsion. Indium-113m marked gastric emptying of water in the milk. In both groups after all meals, oil emptied fastest initially, slowing later; and oil emptied three to four times faster when 60 g vs 15 g were ingested. There were no significant differences between the groups of subjects with respect to gastric emptying of the spaghetti meals, but the pancreatic-insufficient subjects emptied both oil and water faster from the milk emulsion than did the normal subjects. The slower emptying of oil in the normal subjects was associated with significantly more layering of oil to the top of the intragastric milk emulsion.     

Lactose malabsorption among the Pima indians of Arizona

Lactose loading tests and other means were used to determine the pattern of primary "adult" lactose malabsorption (LM) and milk use among 171 subjects, including 122 children and 49 adults, almost all of them Pima Indians of Arizona. LM develops at quite young ages in full-blooded Pima children: already in the 3- to 4-year age group, 40% had LM. Of 62 full-blooded Indians (greater than or equal to 4 years of age), 59 (95%) had LM. Of 41 Indians (greater than or equal to 4 years) who were of mixed Indian-northern European ancestry, however, only 25 (61%) had LM, and, among them, prevalence of LM correlated with degree of northern European admixture. Whereas only 21% of Pima lactose absorbers reported symptoms after the loading test, 72% of malabsorbers did so, with older malabsorbers more likely to experience symptoms. In their everyday lives, only 23% of malabsorbers recognized symptoms brought on by milk consumption, but the percentage of malabsorbers making such an association increased with age. Nevertheless the Pima, adults as well as children, continue to drink reasonable quantities of milk. Family pedigrees are consistent with the hypothesis that adult lactose absorption is inherited as an autosomal dominant trait. Over-all results of this study, moreover, support the geographic hypothesis advanced to explain ethnic or racial differences in prevalence of LM, rather than the induction hypothesis.     

Gastric emptying after gastric bypass

Gastric emptying of two test meals, consisting of ground beef and water and ground beef with 25 percent dextrose was measured with a scintigraphic technique in patients after gastric bypass surgery and in control subjects. Solid emptying was slower and liquid emptying was more rapid after gastric bypass and 25 percent dextrose emptied as rapidly as water. The pattern of gastric emptying after gastric bypass would favour more rapid initial absorption with liquid calories and may also be implicated in the dumping syndromes sometimes seen after gastric bypass.     

Effect of ethanol upon gastric emptying.

The effect of ethanol upon gastric emptying in healthy human subjects was studied by measuring the gastric emptying rates of three 750 ml meals, the osmolalities, energy densities, and pH of which were similar. Meal A, which contained 80 ml alcohol, emptied more rapidly than meal B, which contained 40 ml ethanol and 63.3 g dextrose; and meal B emptied more rapidly than meal C, which contained 126.6 g dextrose but no ethanol. The slower rate of emptying of the dextrose meal (C) was not due to an increased gastric secretory rate, as serial measurements of gastric pH were substantially and significantly higher with this than with the other two meals; nor was it due to a greater degree of duodenogastric reflux, as serial measurements of gastric bile acid concentrations were similar for the three meals. We conclude that the duodenal osmoreceptor mechanism is relatively insensitive to ethanol; that the relationship between energy density and gastric emptying rate does not hold in the case of ethanol; and that the gastro-oesophageal reflux which occurs in response to ethanol is not due to impairment of gastric emptying.     

Glucose and insulin responses to meals containing milk, lactose, glucose or fructose in subjects with non-insulin-dependent diabetes

The postprandial blood glucose and serum insulin responses to liquid test meals containing 40 g carbohydrate from milk, lactose, glucose or fructose and equal amounts of energy were compared in 10 non-insulin-dependent (type 2) diabetic patients. The meals were consumed in random order on consecutive days after an overnight fast. Significant differences (p less than 0.001, ANOVA) were observed between the glucose and insulin responses to the meals. The glucose response was significantly higher after the glucose containing meal and lower after the fructose meal as compared with the other meals. The insulin response was significantly higher after the lactose and glucose meals than after the milk and fructose meals. After the milk and lactose meals the blood glucose responses were similar whereas the insulin response was significantly lower after the milk meal. As lactose apparently was similarly absorbed from the two meals the difference in the insulin response was probably due to different insulinogenic effects of the protein components or to differences in the physical properties of the respective meals.     

Assessment of lactose absorption by measurement of urinary galactose

Individuals with sufficient intestinal lactase hydrolyze ingested lactose to galactose and glucose and these monosaccharides are absorbed. Lactose is not digested completely when intestinal lactase activity is low and the disaccharide is malabsorbed. Breath hydrogen excretion after lactose ingestion is used commonly to diagnose lactose malabsorption. However, no direct tests are currently used to assess lactose absorption. We tested a new method of assessing lactose absorption in 26 healthy individuals. Each subject ingested 50 g of lactose. Participants were evaluated for lactose malabsorption using a standard 3-h breath hydrogen test. In addition, the urinary excretions of galactose, lactose, and creatinine were quantitated for 3-5 h after lactose ingestion. On the basis of breath hydrogen analysis after lactose ingestion, 12 individuals were lactose malabsorbers (defined as a rise in the breath hydrogen concentration of greater than 20 parts per million above the baseline value). The 14 subjects who did not malabsorb lactose by breath hydrogen testing (defined as a rise in the breath hydrogen concentration of less than or equal to 20 parts per million above the baseline value), had significantly more galactose in their urine 1, 2, and 3 h after lactose ingestion than lactose malabsorbers. The ratio of excreted lactose to excreted galactose was significantly decreased in lactose absorbers compared with lactose malabsorbers (p less than 0.001). Determination of the ratio of urinary galactose to urinary creatinine separated lactose absorbers from lactose malabsorbers completely (p less than 0.001). We conclude from this study that the determination of urinary galactose, urinary lactose/galactose ratio, and urinary galactose/creatinine ratio may be used to assess lactose digestion and absorption in healthy adults.     

Gastric emptying of liquids in normal subjects and patients with healed duodenal ulcer disease

We have characterized the dose-response of inhibition of gastric emptying by acid, glucose, and fat in duodenal ulcer (DU) patients and normals (N) matched by age and sex. Gastric emptying was measured by the George technique while intragastric pH was maintained constant by intragastric titration. Acid, glucose, and fat inhibited gastric emptying in a dose-dependent fashion in both groups. DU patients emptied all three types of meals faster than normals, but differences were only seen at the lower doses of glucose or with the less potent doses of acid and fat. With low concentrations of glucose and at all concentrations of acid, DU patients emptied the meals faster than normals only in the first 5 min; but with fat the differences persisted throughout the 30-min test. Differences in gastric emptying of liquid meals in DU patients vs normals are small, and they occur with nutrient as well as acid meals. The variable responses obtained with the different concentrations may explain the inconsistencies found by other workers.     

Prediction of lactose malabsorption in referral patients

Two hundred forty-two patients referred for various gastrointestinal complaints were evaluated for clinical parameters that would predict findings of lactose malabsorption. Breath hydrogen and blood glucose lactose tests were performed after ingestion of 50 g lactose. Presenting complaints, duration of symptoms, and patient demographics such as age, sex, and ethnic heritage were not different between lactose malabsorbers and absorbers as defined by the breath hydrogen lactose test. Foodrelated symptoms in general and after specific foods such as milk, ice cream, cheese, and yogurt were also similar between groups. Prior to testing, 30% of malabsorbers (N=161) and 36% of absorbers (N=81) reported lactoserelated symptoms (P=NS). The blood glucose response to lactose was abnormal in 60% of malabsorbers and 15% of absorbers. This study confirmed our impression that it is difficult to predict lactose absorption status by clinical parameters. The majority of our lactose malabsorber patients were unaware of lactose-associated symptoms. Furthermore, symptom assessment, demographics, food history, and blood glucose testing did not predict abnormal hydrogen responses to lactose.The opinions and assertations expressed herein are those of the authors and are not to be construed as reflecting opinions of the United States Air Force or the Department of Defense.This work has been presented in part at the Annual Scientific Session of the American Gastroenterological Association, San Francisco, California, May 19, 1986, and published as an abstract (Gastroenterology 90:1562, 1986).     

Different gastric,pancreatic, and biliary responses to solid-liquid or homogenized meals

We have compared responses to an ordinary solid-liquid (S) meal and to a homogenized (H) meal of identical composition (sirloin steak, bread, butter, ice cream with chocolate syrup, and water) by measuring simultaneously postprandial gastric, pancreatic, and biliary functions by marker-perfusion techniques. Responses to each (S or H) meals differed strikingly both in magnitude and pattern. S meals elicited a stronger early gastric secretory response (acid, pepsin, and volume) which compensated for faster initial emptying and resulted in higher gastric acidity and volume than after H meals. Further, nutrients ingested with S meals were emptied at a slower rate than H (as evidenced by a more gradual decline in intragastric buffer and osmolality, as well as time required for complete emptying of the meal). This, in turn, prolonged pancreatic and biliary responses since stimulation of these organs continued for as long as meal was delivered into the duodenum. However, early biliary outputs (gallbladder response) were less after S than H, probably because nutrients entered the duodenum more slowly and were initially diluted by rapidly emptying water. The physical characteristics of each meal (encompassing appearance, taste, and form of ingestion) probably accounted for early differences in digestive responses. Later, interactions between gastric (motor and secretory), pancreatic, and biliary functions played a major role. Our findings suggest that gastric, pancreatic, and biliary responses to liquid test meals introduced into the stomach may differ substantially from the presumably more physiological response to ordinary solid-liquid meals.Dr. Summerskill died March 9, 1977.This investigation was supported in part by Research Grant AM 6908 from National Institutes of Health.     

Antroduodenal motor response to solid-liquid and homogenized meals.

The effect of the physical state of food on antroduodenal motor activity and the pattern of the emptying of an aqueous phase marker were examined in 6 healthy volunteers using an intestinal perfusion technique and intraluminal pressure transducers. Ingestion of a solid-liquid meal produced marked phasic changes in pressure in the distal antrum, lasting 92 +/- 10 min (mean +/- SE), while, in contrast, ingestion of the same nutrients in a homogenized state resulted in complete absence of distal antral changes in pressure lasting 133 +/- 12 min. The motor responses of the proximal antrum and duodenum were similar for the two meals. Both meals emptied during a 3-hr period, the pattern of emptying of the aqueous phase marker being similar for the two meals except for the first 40 min, when emptying was more rapid after the solid-liquid meal. The homogenized meal emptied despite the absence of changes in distal antral pressure. The gastrin response was similar for the two meals and is therefore not responsible for the different patterns of antral motility and gastric emptying.     

Relation between gastric emptying rate and energy intake in children compared with adults.

Measurement of gastric emptying rate of solids in children is difficult because the available methods are either invasive or induce a substantial radiation burden. In this study the newly developed 13C octanoic acid breath test was used to examine the gastric emptying rate of solids and milk in healthy children and to compare gastric emptying in children and adults. Fifteen healthy children and three groups of nine healthy adults were studied, using three different test meals labelled with 50 mg of 13C octanoic acid: a low caloric pancake (150 kcal), a high caloric pancake (250 kcal), and 210 ml of milk (134 kcal). Breath samples were taken before and at regular intervals after ingestion of the test meal, and analysed by isotope ratio mass spectrometry. The gastric emptying parameters were derived from the 13CO2 excretion curves by non-linear regression analysis. No significant difference was found between children and adults in the emptying rate of the low caloric solid test meal. In children as well as in adults, increasing the energy content of the solid meal resulted in a significantly slower emptying rate. The milk test meal, however, was emptied at a faster rate in adults and at slower rate in children compared with the low caloric solid test meal. Moreover, the emptying rate of milk in children was significantly slower than in adults. In conclusion, a similar gastric emptying rate of solids but a slower emptying of full cream milk was shown in children of school age compared with adults, using the non-radioactive 13C octanoic acid breath test.     

Effect of vagotomy on gastric emptying

To determine whether pyloroplasty or a disrupted osmoreceptor mechanism is primarily responsible for the increased gastric emptying of hypertonic sugar solutions after vagotomy and pyloroplasty, test meals of 10% glucose (556 mOsm/kg) and NaCl (200 mOsm/kg) were administered to duodenal ulcer patients with no prior operation, after vagotomy and pyloroplasty, and in patients with prior vagotomy, hiatal herniorrhaphy, and no pyloroplasty. Hypertonic glucose meals were emptied more rapidly than normal after both operations. The hypotonic NaCl meal was emptied no faster postoperatively than it was preoperatively. The results rule out pyloroplasty as the primary factor responsible for the observed increased rate of gastric emptying. Instead, the data suggest that the osmoreceptor mechanism described by Hunt is disrupted by vagotomy.Presented in part at the Midwestern Section. American Federation for Clinical Research, Chicago, Ill. Nov 1, 1969.Supported by Veterans Administration Part II Research Funds.     

Effect of first part of duodenum on gastric emptying in dogs: response to acid, fat, glucose, and neural blockade.

Five dogs were prepared, each with a gastric and duodenal fistula (5 cm distal to the pylorus), to study the inhibitory role of the first 5 cm of the duodenum on gastric emptying. The basic design of the experiments was to instill the test meal (300 ml at 37 degrees C, containing phenol red 40 mg 1(-1)) into the stomach and collect it at 1- or 2-min intervals for 10 or 20 min from the duodenal fistula. As the test meal emptied from the stomach it bathed the first 5 cm of duodenum and thus stimulated the appropriate receptor. A Foley catheter with an inflated balloon prevented passage into the second part of the duodenum. Test meals of hypertonic glucose (15%, 865 milliosmoles kg-1) or 20 and 80 mM of sodium oleate emptied at the same rate as water when allowed to bathe the first 5 cm of duodenum, whereas test meals of 100 mM of HCl were slowed. In further studies using neural blocking agents, the emptying of water meals was slowed with subcutaneous atropine sulfate (0.03 and 0.15 mg kg-1), intravenous hexamethonium chloride (10 mg kg-1), and norepinephrine bitartrate (0.04 mg kg-1). The emptying of 100 to 120 mM HCl meals was slowed by subcutaneous atropine sulfate (0.03 and 0.15 mg kg-1), intravenous norepinephrine bitartrate (0.04 mg kg-1), and the intravenous alpha-receptor blocking agents phenoxybenzamine HCl (2 mg kg-1) and phentolamine (2 mg kg-1), was unaffected by intravenous hexamethonium chloide (10 mg kg-1), and was unchanged (1.0 mg kg-1) or slightly slowed (2.0 mg kg-1) by the beta-receptor blocker propranolol. In contrast, acid test meals were emptied at the same rate as water when treated with intravenous guanethidine monosulfate (2 mg kg-1) or intramuscular reserpine (1 mg kg-1), indicating that the acid inhibition was mediated by an adrenergic mechanism. The emptying of water meals was unchanged by these two drugs. The authors suggest that the first 5 cm of duodenum contain receptors for inhibition of emptying of acid but not for fat or hypertonic glucose. Furthermore, the neural blocking studies indicate that the inhibitory effect of acid in the first part of the duodenum is an adrenergic mechanism which appears to be neither alpha nor beta-receptor-mediated.     

Effects of age on lactose malabsorption in Oklahoma Native Americans as determined by breath H2 analysis

Breath H₂ excretion was used to determine lactose malabsorption in 30 healthy females and 30 healthy males between the ages of 3 and 64 yr who were at least 7/8 Native American. The test meal consisted of 5 ml reconstituted nonfat dry milk (0.25 g lactose) per kg of body weight. On the basis of breath H₂ tests in 15 control subjects with normal oral lactose tolerance tests, a response factor of 20 ppm was selected as the upper limit for lactose absorbers. Of the 60 subjects in the study group, 36 (60%) were classified as lactose malabsorbers since they had a response factor of 20 ppm or greater of breath H₂. Only 3 of 20 children (15%) who were under the age of 12 yr were nondigesters of the small lactose dose used in this study. Approximately 82 percent (82.5%) of subjects who were 13 yr and older were lactose malabsorbers. Adolescence appears to be the period in which malabsorption of lactose becomes evident in Native North Americans.Supported by the Nutrition Foundation, Inc., New York, New York; Biomedical Sciences Support Grant (USPH) 5-S05-RR7077 to The Research Foundation, Oklahoma State University.     

Gastric emptying and intestinal transit of hyperosmolar solutions in relation to indomethacin and certain gut polypeptides in the rat

The present study in the rat demonstrates an inhibitory mechanism of gastric emptying, sensitive to the osmolality of a liquid meal. Gastric emptying and intestinal transit were studied in groups that differed with regard to the osmolality of the gastric or duodenal instillation, experimental time, and indomethacin treatment. By intragastric instillation animals were fed an aqueous solution containing the nonabsorbable marker 51CrO2-4. After certain fixed time intervals the rats were killed and the stomach and small intestine were dissected out en bloc. The distribution of the isotope along the gastrointestinal canal was then determined. Intestinal transit was evaluated in a similar manner. The marker solution was introduced into the duodenum. A hyperosmolar solution, 1200 mOsm kg-1, was emptied from the stomach significantly more slowly than was an iso-osmolar solution, 300 mOsm kg-1. Of the iso- and hyper-osmolar solutions 87% and 74%, respectively, were emptied in 1 h. The isotope distribution along the intestinal canal after intraduodenal instillation was not affected by the osmolality of the installation. The osmotic inhibition of gastric emptying was not affected by indomethacin treatment (4 mg kg-1) or related to elevated plasma levels of gastrin, neurotensin, somatostatin, or gastric inhibitory polypeptide.     

A role for pancreatic polypeptide in the regulation of gastric emptying and short-term metabolic control

CONTEXT: Previous studies using pancreatic polypeptide (PP) infusions in humans have failed to show an effect on gastric emptying, glucose metabolism, and insulin secretion. This might be due to the use of nonhuman sequences of the peptide. OBJECTIVE: The objective of this study was to use synthetic human PP to study gastric emptying rates of a solid meal and postprandial hormone secretion and glucose disposal as well as the gastric emptying rate of water. DESIGN: This was a single-blind study. SETTING: The study was performed at a university hospital. PARTICIPANTS: Fourteen healthy adult subjects were studied. Interventions: Infusion of saline or PP at 0.75 or 2.25 pmol/kg.min was given to eight subjects (gastric emptying of solid food), and infusion of saline or PP at 2.25 pmol/kg.min was given to six subjects (gastric emptying of water). MAIN OUTCOME MEASURES: The main outcome measures were gastric emptying of solids (scintigraphy), hunger ratings (visual analog scale), and plasma concentrations of PP, insulin, glucagon, somatostatin, glucagon-like peptide 1, glucose, and gastric emptying of plain water (scintigraphy). RESULTS: PP prolonged the lag phase and the half-time of emptying of the solid meal. The change in hunger rating, satiety, desire to eat after the meal, or prospective consumption was not affected. The postprandial rise in plasma glucose was prolonged by PP. The postprandial rise in insulin was also delayed by PP. PP had no significant effect on the emptying of water. CONCLUSIONS: PP inhibits gastric emptying of solid food and delays the postprandial rise in plasma glucose and insulin. PP is suggested to have a physiological role in the pancreatic postprandial counterregulation of gastric emptying and insulin secretion.     

Lactase deficiency and lactose intolerance-related symptoms in adult healthy subjects from western France]

The prevalence of lactase deficiency (LD) and lactose intolerance is not well known in France. Using breath hydrogen and methane analysis after 50 g oral lactose load, we investigated the prevalences of LD, lactose intolerance, and methane producer status in 102 healthy adults born in western France, and we examined the relationships between these parameters and the daily milk consumption. In 10 subjects with LD and lactose intolerance, we studied the reproducibility of the lactose hydrogen breath test results for the diagnosis of LD and lactose intolerance and estimated the quantity of lactose malabsorbed in comparison with the lactulose hydrogen breath test. The prevalence of LD was 23.4 percent and symptoms of lactose intolerance were observed in 50 percent of the 24 subjects with LD. The daily milk consumption was not significantly different in the 24 subjects with LD and in the 78 subjects without LD (281 +/- 197 vs 303 +/- 217 ml/24 h). The prevalence of methane producer status was 42.1 percent. The symptomatic group of lactose malabsorbers (n = 12) was characterized by a shorter lactose mouth to caecum transit time (39 +/- 20 vs 88 +/- 48 min; P less than 0.05), and more marked hydrogen production (6.1 +/- 2.3 vs 3.4 +/- 2.4 10(3) ppm.min; P less than 0.04). In the 10 subjects with LD and lactose intolerance, the hydrogen breath test was reproducible for diagnosis of LD and lactose intolerance, and for hydrogen production. The quantity of lactose malabsorbed was 60 percent. In France, symptoms of lactose intolerance are not severe and do not affect the daily consumption of milk and dairy products.     

Influence of meal weight and caloric content on gastric emptying of meals in man

This study was designed to assess the relative influence of meal weight and caloric content on gastric emptying of liquid and solid meals in man. A dual radioisotopic method which permits noninvasive and simultaneous measurement of liquid-and solid-phase emptying by external gamma camera techniques was employed. Nine healthy volunteer subjects ingested 50-,300-, and 900-g lettuce and water meals adjusted to either 68, 208, or 633 kcal with added salad oil. The following observations were made: (1) absolute emptying rates (grams of solid food emptied from the stomach per minute) increased directly and significantly with meal weight; (2) increasing meal total caloric content significantly slowed solid food gastric emptying but did not overcome the enhancing effect of meal weight; and (3) liquid emptying rates were uninfluenced by meal total kcal amount.The authors wish to express their appreciation to the Salt Lake Veterans Medical Center, Medical Research Service for their support.     

Effect of intragastric volume and osmolality on mechanisms of gastroesophageal reflux in children with gastroesophageal reflux disease

OBJECTIVE: Both transient lower esophageal sphincter (LES) relaxations (TLESRs) and periods of low/absent LES pressure (LESP) are the main mechanisms of gastroesophageal reflux. These events are believed to be triggered by stimuli from different areas of the upper GI tract. We aimed at investigating the relationship between LESP profile and gastric emptying and distension after meals of different composition in 30 children with gastroesophageal reflux disease (median age 7.0 yr, range 12 months-12 yr). METHODS: Recordings of LESP and intraesophageal pH for 1 h fasting and for 2 postprandial h were performed with a perfused sleeve catheter and flexible electrode, respectively; gastric emptying and distension of antral area were simultaneously recorded with real-time ultrasonography. Ten patients had a standard meal (group A), 10 had a high-volume meal (group B), and 10 had a high-volume and osmolality meal (group C). RESULTS: Postprandial esophageal acid exposure was significantly higher in patients of groups B and C than in patients of group A (p < 0.01); it was also more prolonged in patients of group C than in subjects of group B (p < 0.05). A higher postfeeding rate of reflux episodes caused by TLESRs was detected in patients of groups B and C as compared with patients of group A (p < 0.01). This increase did not statistically differ in patients of groups B and C. Patients of group C exhibited a higher postprandial rate of reflux episodes associated with low/absent tone of the LES as well as a more prolonged gastric emptying time and a higher postfeeding gastric distension as compared with patients of groups A and B (p < 0.01). Finally, a significant correlation was only found between the postprandial rate of reflux events resulting from low/absent LESP and the degree of antral distension in patients of group C (p < 0.01). CONCLUSION: Gastroesophageal reflux is worsened by increasing the volume and osmolality of meals through significant changes of LESP. Meals of high volume and meals with high volume and osmolality cause a comparable increase of reflux episodes as a result of TLESRs. However, meals with high volume and osmolality cause the higher degrees of esophageal acid exposure than meals with high volume resulting from a higher rate of reflux episodes associated with low/absent LESP. This finding correlates with a high postfeeding antral distension.     

Effects of nutrients on gastrointestinal motility and gastric emptying after distal gastrectomy with Roux-Y gastrojejunostomy in dogs

The aim of the study was to clarify whether nutrients are still capable of slowing gastric emptying following Roux-Y gastrectomy, as in normal dogs. Gastrointestinal motility and gastric emptying of acaloric and nutritive meals with different viscosities were measured in normal dogs and after a two-thirds Roux-Y gastrectomy. In gastrectomized dogs low-viscosity nutritive meals emptied unduly rapidly in an initial phase, although the frequency and spread of contractions, ie, the propulsive activity of the jejunal Roux limb were diminished. A slow emptying rate during the following period was due to a long-lasting inhibition of gastric and jejunal motility. Medium-viscosity nutritive meals emptied in gastrectomized dogs as slowly as in normal animals, but this effect was primarily caused by the meal viscosity and only secondarily by the nutrients. It is concluded that following Roux-Y gastrectomy a regulation of gastric emptying is preserved; however, the onset of an effective control is delayed, resulting in a rapid initial emptying of low-viscosity meals.Studies were supported by the Deutsche Forschungsgemeinschaft grant Eh 64/3-1.