Gastric acidity and motility

Disturbed gastroduodenal motility in patients with active and healed duodenal ulceration

Disordered gastroduodenal motility may promote duodenal ulceration by allowing prolonged acid contact with the duodenal mucosa. Using a multilumen perfused catheter incorporating 3 pH microelectrodes, antral and duodenal pH and antropyloroduodenal pressure activity were recorded in 36 subjects (10 with healed duodenal ulceration, 11 with active duodenal ulceration, and 15 healthy volunteers) during fasting and after a radiolabeled solid test meal. Correct pH probe/catheter position was continuously verified by recording transmucosal potential difference across the pylorus. Patients with active and healed duodenal ulcer had similarly disordered gastroduodenal motility. The chief abnormalities consisted of an increase in postprandial duodenal retroperistalsis (healed duodenal ulceration, 12 +/- 1 events per hour; active duodenal ulceration, 12 +/- 1; control, 6 +/- 1; mean +/- SEM: healed and active duodenal ulceration vs. control, P = 0.004 and P = 0.03, respectively), a reduction in pressure waves sweeping aborally through the duodenum after the meal (healed duodenal ulceration, 22 +/- 4 events per hour; active duodenal ulceration, 23 +/- 3; control, 34 +/- 4: healed and active duodenal ulceration vs. control, P = 0.04 and P less than 0.05, respectively), and an increased incidence of atypical, complex forms of coordinated duodenal motor activity throughout the study (postprandial data; healed duodenal ulceration, 8 +/- 1 events per hour; active duodenal ulceration, 10 +/- 1; control, 4 +/- 1: healed and active duodenal ulceration vs. control, P = 0.02 and P less than 0.02, respectively). In addition, gastric emptying of the solid test meal was significantly delayed in healed, but not active, duodenal ulceration [half-emptying time, healed duodenal ulceration 185 minutes (117-235); active duodenal ulceration 102 minutes (80-200); control 107 minutes (78-130): healed duodenal ulceration vs. control, P less than 0.009]. Duodenal bulb pH was similar in controls and patients with active duodenal ulceration; however, bulb pH was less than 4 for a significantly greater period of time in healed duodenal ulceration compared with active ulcer patients, particularly after the meal. In conclusion, duodenal ulcer disease is associated with disturbed gastroduodenal motility, even when the ulcer is quiescent and when intraduodenal acidity is low. In healed duodenal ulceration, disturbed motility may promote ulcer relapse by impairing acid clearance from the bulb. However, in active ulceration other factors such as mucosal bicarbonate secretion may have a more influential role in determining intraduodenal pH.

Gastric emptying in deformed stomach

To evaluate the relationship between the onset of peptic ulcer and gastric emptying, some factors which were thought to regulate gastric emptying, i.e. the stage of the ulcer, the location of the ulcer and gastric acidity were studied in cases of gastric ulcer with deformed stomach and were proven to have little influence on gastric emptying. Further, the main cause of delayed gastric emptying was revealed to be the deformity itself, because the shortening of the distance from the gastric angle to the pyloric ring at the lesser curvature (sac-shaped stomach) and the indentation of the corpus ventriculi (hourglass-shaped stomach) significantly delayed gastric emptying. Moreover, it was found that the healing of gastric ulcer was delayed in cases of deformed stomach with delayed gastric emptying when the ulcer was at an active stage. Therefore the improvement of gastric emptying by some methods was thought to be necessary to promote ulcer healing and prevent ulcer recurrence in gastric ulcer patients who had a deformed stomach.

Scintigraphic evaluation of gastric emptying

There has been recent, renewed interest in studies of gastric emptying due in part to the introduction of new therapies for peptic ulcer diseases and attempts to better understand gastric physiology. Of the methods available for studying gastric emptying patterns, nuclear medicine techniques are optimal due to their noninvasive character, reproducibility and quantitative ability. The modulation of gastric emptying is multifactorial, and includes motor control, electrical activity, hormonal influences, and the composition of the meal itself: liquid vs solid; protein, carbohydrate and fat content; fiber or particle size; osmolality; pH; and pharmacologic agents. Because of the ease of performing gastric emptying studies using radiolabeled physiologic meals, these tests are being employed with increasing frequency in the evaluation of patients with disorders such as diabetic gastroparesis, postgastrectomy gastroparesis or dumping syndrome, and in the study of normal gastric physiology in man. Present data suggests that combined liquid-solid, dual radionuclide studies afford the greatest information regarding simultaneous gastric emptying patterns of liquid and solid components of a meal, and that single radionuclide, solid tests of gastric emptying are the more sensitive technique for determining subtle abnormalities of gastric emptying, when only a single tracer is employed.

An improved apparatus for intragastric titration in the conscious dog

An apparatus for automatic intragastric titration with on-line display of results has been described. The apparatus has been validated by titration of exogenous acid injected into the test meal in a reservoir and in vivo by assessing the secretory response of a dog with a gastric fistula to a test meal. A titration display unit provides a record of the secretory response both as a digital printout and a bar chart display. Cimetidine (2 mg kg-1h-1) significantly reduced the secretory response to a test meal.

Gastric acid secretion rate and buffer content of the stomach after a rice- and a wheat-based meal in normal subjects and patients with duodenal ulcer

The study describes gastric acid secretory response to a rice-based and a wheat-based meal over a prolonged period of five hours and buffer content of the stomach in five normal and seven duodenal ulcer subjects from the rice-eating eastern Indian population. The results suggest that (1) the meal-mediated gastric acid secretory response in duodenal ulcer subjects is much higher than in the controls, even though the histamine stimulated response is similar, (2) the type of meal, whether rice and fish based or wheat and meat based, does not influence the acid secretory response, and (3) the duodenal ulcer subjects in this area, two hours after a meal, have a buffer capacity similar to the controls.

Effect of cigarette smoking on gastric emptying

Gastric emptying after a test meal was studied in 17 normal volunteers--10 habitual smokers and seven non-smokers. The solid component of the test meal was labelled with technetium and the liquid component with indium. After one meal the habitual smokers smoked two cigarettes. Emptying curves were produced for both technetium and indium, and the differences between curves for meals with and without cigarettes were analysed. Cigarette smoking accelerated the rate at which the liquid component of a meal left the stomach. This may be important in the pathogenesis of duodneal ulcer and the delay in healing caused by cigarette smoking.

Serum gastric inhibitory polypeptide (GIP) in duodenal ulcer disease: relationship to glucose tolerance, insulin, and gastrin release

Serum immunoreactive gastric inhibitory polypeptide (IR-GIP), gastrin (IRG), and insulin (IRI) were estimated in 41 normal weight patients with duodenal ulcer (DU) and 25 age-matched controls in response to a high calorie liquid test meal. 28 out of 41 DU patients had a hyperglycaemic glucose response during the test meal, and 15 had a pathological oral glucose tolerance test. Fasting and food-stimulated IR-GIP and IRG levels were significantly elevated in the DU patients. Serum IRI also increased to significantly higher levels in DU patients after the test meal. The degree of the greater hormone response was dependent on the glucose increase after the test meal in the case of insulin and GIP, but not in the case of gastrin. It is concluded: firstly, that a faster glucose absorption (possibly due to rapid initial gastric emptying or increased intestinal motility) is responsible for the high and short-lasting glucose peak and the increased GIP and insulin secretion; secondly, that the GIP response could well be causally related to the insulin response; thirdly, that hyposcretion of GIP is ruled out as a possible factor in the pathogenesis of gastric acid hypersecretion of duodenal ulcer patients.

Gastric emptying of wholemeal and white bread

We studied the rates at which solid and liquid leave the stomach after meals of wholemeal and white bread by using a double isotope technique. There was no difference in the rates at which the solid phases of the gastric contents left the stomach but liquid left the stomach significantly more rapidly with white bread than with wholemeal bread. Furthermore, the amount of liquid leaving the stomach unaccompanied and therefore unbuffered by solid was significantly greater after while bread than wholemeal bread. These findings may be of significance in the pathogenesis of duodenal ulcer and they provide a rational basis for a possible form of dietary treatment.

Effect of fundic distension on gastric acid secretion in man

The effect of distension of the fundus and body of the stomach on gastric acid secretion was studied in 26 patients with duodenal ulcer and six healthy subjects. Graded distension produced by inflating a rubber balloon to volumes of 150, 300, and 600 ml resulted in significant sequential increments of acid output. The secretory response outlasted stimulation by at least one hour. In both groups of subjects, the highest acid output obtainable with fundic distension amounted to just above 50% of the maximum secretory response evoked by intravenous infusion of pentagastrin. A significant correlation was found between the peak secretory rates observed during fundic distension and after pentagastrin stimulation. It is concluded that distension of the oxyntic gland area in man is a potent stimulus for gastric secretion of acid and that patients with duodenal ulcer are no more sensitive to this stimulus than healthy subjects.

Gastric emptying in control subjects and patients with duodenal ulcer before and after vagotomy

The emptying of a solid meal labelled with Indium 113mDTPA from the stomach was studied with a gamma camera in 26 normal subjects, 27 patients with duodenal ulcer, on 41 occasions after truncal vagotomy and pyloroplasty and 38 times after highly selective vagotomy. Applying the method of principal component analysis to the results, differences were detected between control and duodenal ulcer subjects and two probable subgroups of duodenal ulcer were observed. Half emptying times did not reveal these patterns. After vagotomy, delayed emptying was general at one week. At one month, patients after highly selective vagotomy had a more normal result than those with truncal vagotomy and pyloroplasty (TV), but by six months no significant difference in overall emptying rate was found, although changes in the pattern of gastric emptying persisted in some patients after TV.

Gastric acid secretion rate and buffer content of the stomach after eating. Results in normal subjects and in patients with duodenal ulcer

New methods are described by which the buffer content and the rate and pattern of net gastric acid secretion in human subjects fed normal meals can be measured by use of sodium bicarbonate infusion to control intragastric pH. With these techniques, it was shown that the rate of acid secretion in response to a steak meal in seven duodenal ulcer patients was twice the rate achieved in six control subjects and that the amount of acid secreted after eating exceeded the peak histamine response in the ulcer patients but not in the controls. Meal-stimulated acid secretion, expressed as a function of the peak histamine response, was roughly correlated with the serum gastrin concentration (r = 0.45), but it was concluded that other factors must also contribute to the higher than normal secretory responses to a meal found in duodenal ulcer patients. Measurement of buffer content of the stomach revealed that the duodenal ulcer patients emptied the meal buffer at a much more rapid rate than the normal subjects. By 2 h after eating, the ulcer subjects had less than half as much buffer in their stomachs as the controls. The combination of acid hypersecretion and rapid buffer emptying leads to abnormally high gastric acidity after a meal in duodenal ulcer patients. These results suggest that, in addition to a large parietal cell mass, parietal cell responsiveness to a meal and the rate of buffer emptying may be important in the pathogenesis of duodenal ulcer.

Effect of metoclopramide on gastric function in man

The effects of metoclopramide on gastric emptying and gastric secretion have been assessed in man using the double sampling test meal. Metoclopramide increases the rate of emptying of the stomach. The magnitude of the effect is directly related to the initial emptying time. Metoclopramide has no effect on the acid response to a water test meal.