Ian L. MacGregor

The Effect of Acute Hyperglycemia on Gastric Emptying in Man

Older work in man with meals of carbohydrates in water has indicated that such meals slow gastric emptying in proportion to their osomolarities. Nevertheless, different carbohydrates have been found to have differing efficacies per milliosmole. One possibility which would explain such discrepancies among carbohydrates is that hyperglycemia induced by carbohydrate absorption itself contributes to the slowing of gastric emptying. To test this possibility, normal subjects were made acutely hyperglycemic with intravenous loads of glucose during the ingestion of various liquid test meals, and rates of gastric emptying of these meals were compared in the same subjects during periods of induced hyperglycemia with rates of gastric emptying under euglycemia conditions. Induced hyperglycemia significantly slowed the rate of emptying of meals containing fat + protein, or protein, but did not significantly alter emptying of meals containing only NaCl. It is concluded that hyperglycemia does exert some effect on gastric emptying, but that these effects of hyperglycemia are variably expressed, depending on the presence of other factors which themselves slow gastric emptying.

99mTc-Tagged chicken liver as a marker of solid food in the human stomach

Past measurement of gastric emptying of solid food in man has depended on external counting of surface-absorbed isotopes without verification that isotopic labels remain attached to solid food in the stomach. In this study chicken liver was isotopically labeled with99mTc incorporated uniformly and intracellularly throughout the liver substance.In vitro studies showed less than 10% loss of99mTc from liver incubated with pepsin HCl. By contrast, up to 90% of51Cr adsorbed to scrambled eggs became detached under similar conditions. In feeding experiments less than 10% of99mTc was liberated from fed99mTc liver, while significantly more51Cr became detached from egg under identical intragastric conditions. We conclude that99mTc-tagged chicken liver is an adequate marker of the rate of emptying of solid food and appears to be more reliable than51Cr-labeled scrambled eggs from which51Cr dissociates in the stomach.

GASTRIC EMPTYING OF SOLID FOOD IN NORMAL MAN AND AFTER SUBTOTAL GASTRECTOMY AND TRUNCAL VAGOTOMY WITH PYLOROPLASTY

Alterations in gastric emptying are considered contributory to many sequelae of peptic ulcer surgery. The application of a validated method of firmly tagging solid food has enabled the measurement of the rates and patterns of gastric emptying in normal subjects, subtotal gastrectomy, and vagotomy and pyloroplasty (V&P). Normal persons emptied with a linear pattern at a mean rate of 27.96% per hr. Subtotal gastrectomy patients showed up to three phases in their emptying pattern, which, over all, approximated an exponential pattern with a mean rate constant of 0.030 min-1 and calculated t1/2 of 23.3 min. V&P subjects divided into two groups: (1) slow emptying with a linear pattern and mean rate of 17.64% per hr; (2) rapid emptying with exponential pattern and mean rate constant of 0.039 min-1, t1/2 of 17.7 min. The slow gastric emptying rate and slow passage of chyme through the small intestine in one-half of the V&P group presumably allows greater efficiency of digestion and absorption and may account for the over-all less severe nutritional disturbances after V&P.

THE EFFECT OF ACUTE HYPERGLYCEMIA ON MEAL-STIMULATED GASTRIC, BILIARY, AND PANCREATIC SECRETION, AND SERUM GASTRIN

The effects of hyperglycemia on pancreatic, biliary, and gastric secretory responses to meals have not been hitherto quantified in man. In the present study seven normal volunteers were fed on two occasions a 500-ml liquid test meal containing fat and protein. During one of the meals the subjects were made acutely hyperglycemic with intravenous glucose, whereas in control experiments, each subject received intravenous saline in place of glucose. A jejunal perfusion method was used to measure pancreatic outputs of trypsin and biliary outputs of bile salts for 150 min after the meal; the same method was used to quantify indirectly the amount of acid secreted by the stomach in the 150-min period. Serum gastrins were also measured basally and at intervals after the meal. Hyperglycemia suppressed serum gastrin, gastric acid production, trypsin secretion, and bile salt output in response to the test meal.

Gastric, pancreatic, and biliary secretion and the rate of gastric emptying after parietal cell vagotomy☆

We compared the gastric, pancreatic, and biliary secretory responses to a liquid test meal and the rates of gastric emptying of liquid and solid test meals in six patients at least 1 year after parietal cell vagotomy with eight unoperated subjects, one with duodenal ulcer disease and seven normal control subjects. Parietal cell vagotomy decreased gastric acid secretion to one third of normal, but total trypsin and bile salt secretion during the first 150 postcibal minutes were normal. The liquid test meal emptied from the stomach faster after parietal cell vagotomy, the pattern of emptying being exponential in the vagotomy patients and linear in the normal subjects. The rate of gastric emptying of a liquid meal, although faster than normal, was less precipitous after parietal cell vagotomy than after truncal vagotomy plus drainage or subtotal gastrectomy, and trypsin and bile salt concentrations were not diluted to abnormal levels, as occurs after these other procedures. Furthermore, emptying and dispersion of solid food remained normal after parietal cell vagotomy. These findings probably explain, at least in part, the decreased incidence of postprandial dumping and diarrhea that accompanies parietal cell vagotomy compared with the other popular operations for duodenal ulcer.

Slowed rate of gastric emptying of solid food in man by high caloric parenteral nutrition.

We studied the effect of high caloric parenteral nutrition on the rate of gastric emptying of solid food. The linear pattern of gastric emptying was not altered by parenteral nutrition, but the gastric emptying rate was consistently slowed. The degree of slowing of gastric emptying while on parenteral nutrition correlated with the increase in blood glucose induced by the intravenous nutrient load. These findings may explain the oral food intolerance displayed by some persons receiving both oral and high caloric intravenous nutrition.

Effect of pentagastrin infusion on gastric emptying rate of solid food in man

The effect of intravenous pentagrastrin (4 μg/kg-hr) on the rate of gastric emptying of solid food was studied in 6 normal men. A mean consisting of one99mTc-tagged chicken liver mixed with beef stew and taken with 200 ml of water was followed on its passage through the gastrointestinal tract by intermittent scanning with a gamma camera. The rate of the linear gastric emptying pattern was slowed by pentagastrin in every individual. The pH and titratable acidity of the gastric contents were similar in the pentagastrin and the control infusions. Neutralization of the gastric contents with bicarbonate in the pentagastrin studies did not alter gastric emptying rates. The results indicate that pentagastrin slows gastric emptying of solid food in man by an effect apart from acid secretion. The myoelectrical correlates of such an observation are uncertain.

The effect of hyperthyroidism on gastric emptying rates and pancreatic exocrine and biliary secretion in man

Malabsorption and diarrhea in hyperthyroidism has been attributed in part to an increased rate of gastrointestinal transit as measured with barium sulfate suspension. Data are unavailable on the effect of hyperthyroidism on gastric emptying rates of normal food and pancreatic enzyme secretion. These functions have been studied in 4 hyperthyroid patients and compared to results obtained when treatment achieved euthyroidism. Pancreatic trypsin secretion was half the euthyroid level in the hyperthyroid state. No significant change in bile salts occurred, although there was a tendency for a greater proportion of dihydroxy bile salts while hyperthyroid. Gastric emptying rates of a mixed fat, protein, and carbohydrate liquid meal were normal. Similarly the gastric emptying rate of a beef stew plus chicken liver meal was normal. We conclude that in hyperthyroidism gastric emptying rates of “physiologically active” food is normal. Pancreatic enzyme secretion is depressed in hyperthyroidism and may contribute to maldigestion.

A Cause of Hyperamylasemia Associated with Chronic Liver Disease

The cause of hyperamylasemia associated with chronic liver disease is unclear. In an attempt to identify the tissue of origin of hyperamylasemia in 3 patients with chornic active hepatitis their serum was isoelectrically focused. The isoamylase patterns obtained were compared to those of pancreatic and salivary amylase. The apparent salivary gland origin of the excessive blood amylase in the patients studied was substantiated by radiological demonstration of parotid sialoectasia in one patient and histological evidence of sialoadenitis in another. Further evidence was the coincident isoelectric points of the predominant isoamylase in the sera of the liver disease patients and of patients with parotid inflammatory disease. Hyperamylasemia associated with chronic liver disease may be of salivary gland origin and as such forms part of the spectrum of extrahepatic manifestations of chronic active hepatitis.

Nonabsorbable indicators. The effect of protein on phenol red and polyethylene glycol determination.

The effect of the proteins in milk powder and egg albumin on the determination of phenol red and polyethylene glycol (P.E.G.) has been determined. Both proteins bind phenol red as whole proteins and after partial digestion. Egg albumin interferes with the turbidimetric estimation of P.E.G. increasing the turbidity.