Effect of gastrectomy on release of gut hormones

We investigated the effect of gastrectomy on the digestive system in 87 postoperative long-term survivors under test meal or egg yolk load. After test meal, gastrin and secretin responses were decreased in each of groups of proximal gastrectomy (PG), distal gastrectomy with Billroth-I (DG-B1), that with Billroth-II (DG-B2), total gastrectomy with interposition (TG-I), and that with Roux-Y (TG-RY). However, sufficient acid-secretors after partial gastrectomy showed secretin responses comparable to controls. Furthermore, cases of total gastrectomy given betain-hydrochloride with test meal increased secretin responses. Serum glucose response was higher in the TG-RY group while insulin response was high in the TG-RY and DG-B2 groups, compared with controls. GLI response was high in all groups compared with controls. Postgastrectomy gallstone occurred in 11.6%. Yolk-induced contraction of the gallbladder was decreased, and CCK release increased, for several years postoperatively. Gallbladder contraction with CCK was reduced for one year postoperatively. The contraction was reduced in persons with gallstone than those without it. This study shows that the digestive function after gastrectomy depends on acidification and duodenal passage of food, and that reduced contraction with CCK plays an important role in hypokinesis of the gallbladder.     

Human gastrin response to secretin after vagotomy.

The gastrin response to a liquid meal with and without secretin infusion was studied in nine patients undergoing selective or truncal vagotomy with pyloroplasty for duodenal ulcer disease. Fasting gastrin levels were significantly increased in eight of nine patients after vagotomy, but secretin infusion did not consistently suppress these basal gastrin levels either pre- or postoperatively. Infusion of secretin did significantly lower the integrated gastrin response to feeding both pre- and postoperatively in eight of nine patients. Vagotomy alone did not significantly alter the integrated gastrin response to feeding. This data gives evidence that secretin infusion remains a helpful diagnostic test, differentiating those patients with recurrent ulcer and elevated gastrin levels postvagotomy from those patients with occult Zollinger-Ellison syndrome.     

Gut hormone profiles after various types of gastrointestinal surgery

Gastrointestinal and pancreatic hormone responses to test meal or oral glucose were studied in totally gastrectomized patients (TG), subtotally gastrectomized patients with BI and BII, patients with pylorus preserving gastrectomy (PPG), a case of massive (4m 15 cm) bowel resection (MBR) and patients with pancreatoduodenectomy (PD), and compared to the pattern of healthy control subjects (HC). Plasma IRI, GIP and GLI responses to meal in TG and BII were significantly higher, and those in BI appeared to be higher than those in HC. In contrast, those hormonal patterns in PPG were similar to HC. Thus, it seemed that PPG was more physiological than any other gastrectomies in the viewpoints of GI hormonal patterns. In a case of MBR, plasma GLI response to oral glucose, expressed as peak/basal GLI, was significantly higher compared to HC. This higher GLI responsiveness together with remarkably high plasma gastrin level in this case might have a role in stimulating the adaptative changes found after MBR. IRI and GIP responses to oral glucose were impaired following PD without pancreatojejunostomy, while after operating pancreatojejunostomy, those responses restored in part which might suggest the significant role of the pancreatic juice into the jejunum in releasing mechanism of these hormones.     

Postprandial plasma secretin and CCK release in patients with gastrectomy and pancreatoduodenectomy]

Postprandial plasma secretin and CCK release were investigated in patients with gastrectomy and pancreatoduodenectomy reconstructed by Billroth-I, Billroth-II, Roux-en-Y and Child's methods. Plasma secretin response were significantly decreased in patients with B-I and B-II reconstruction after gastrectomy, especially in total gastrectomized patients with Roux-en-Y reconstruction, which might be resulted from the reduced gastric acid secretion following gastrectomy. CCK release was not significantly changed in patients with various reconstructions after gastrectomy compared with control group. In patients with pancreatoduodenectomy reconstructed by Child's method plasma secretin and CCK release were significantly decreased as compared with normal controls.     

Die Gastrektomie nach Longmire im Tiermodell: Postoperative Veränderungen bei der Fettresorption sowie der Hormone Cholezystokinin und Sekretin

Zusammenfassung Im Tierversuch wurde die Resorption von freien Fettsauren und Triglyzeriden nach Gastrektomie untersucht. Die Antwort der gastrointestinalen Hormone Cholezystokinin und Sekretin wurde nach einer definierten enteralen Fettbelastung mit Lipofundin MCT 20% gemessen. Die Fettresorption untersuchten wir an 3 Versuchsgruppen, die sich anatomisch (Vorhandensein bzw. Fehlen des Magens) und hinsichtlich des Ortes der Fettapplikation (intragastral bzw. intraduodenal) unterschieden. Die Verabreichung einer Testmahlzeit unter Umgehung des Magens bewirkte hinsichtlich des Fettstoffwechsels eine verzögerte Resorption der Fettsäuren, bei den gastrektomierten Tieren resultierte zusätzlich eine vermehrte Triglyzeridresorption. Mittel- und langkettige Fettsäuren setzten bei der Ratte einen adäquaten Reiz zur Stimulation der gastrointestinalen Hormone CCK und Sekretin. Bei den Gastrektomierten zeigte sick eine generelle Hormonhypersekretion im Nüchternzustand. Dem Ausbleiben der zu erwartenden CCK-Antwort auf den Fettreiz stand eine voll erhaltene Sekretinstimulierbarkeit auf angehobenem Niveau gegenüber. Die Gewichtsentwicklung der gastrektomierten Tiere war deutlich beeinträchtigt, eine konstante Gewichtszunahme auf niedrigem Niveau über den einjährigen Untersuchungszeitraum hinweg wurde konstatiert. Veränderungen in der Morphologie und Quantität der CCK-Zellen im Duodenum konnten ausgeschlossen werden.

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Changes in lipid absorption and the secretion of cholecystokinin and secretin

In this animal study we investigated the absorption of free fatty acids and triglycerides after gastrectomy. The levels of the hormones cholecystokinin and secretin were measured in response to a controlled enteral fat load (Lipofundin 20% MCT emulsion). We studied fat absorption in three groups of animals: the gastrectomy group in which lipid emulsion was administered in the duodenum, and two groups of controls that received the same infusion in the duodenum or stomach, respectively. Infusing the fat load directly into the duodenum, rather than the stomach, resulted in delayed absorption of fatty acids. In the gastrectomized animals there was, in addition, increased absorption of triglycerides. Medium- and long-chain fatty acids were found to be an adequate stimulus for secretion of the gastrointestinal hormones cholecystokinin (CCK) and secretin. In the gastrectomized group, higher baseline levels of both CCK and secretin were observed. CCK showed no response to the lipid stimulus, whereas a secretin response was observed over and above the raised baseline level. The gastrectomized animals showed a markedly restricted growth rate, as measured by body weight; however, they continued to gain weight in a linear fashion up to the end of the study period. No alterations in morphology of CCK-secreting cells were found.

     

Effects of various forms of gastric surgery on gut hormones and pancreatic secretions

Effects of various forms of gastric surgery on gut hormones and pancreatic secretions were examined using canine models. These operative procedures included simple laparotomy (group A; n = 13), truncal vagotomy with pyloroplasty (B; n = 17), selective proximal vagotomy (C; n = 17), proximal gastrectomy with pyloroplasty (D; n = 6), proximal gastrectomy with truncal vagotomy and pyloroplasty (E; n = 7), and distal gastrectomy (F; n = 19). The mean fasting serum gastrin and secretin levels (pg/ml) were 71.0, 82.5 in A, 94.0, 97.7 in B, 62.1, 108.1 in C, 58.2, 123.0 in D, 91.2, 138.6 in E, and 50.9, 74.5 in F, respectively. The mean value of plasma pancreatic glucagon (pg/ml) showed 73.6, 109.9, 106.8, 47.2, 37.8, and 74.5 in each of the six groups. Significant correlations were observed between values of serum lipase and those of serum gastrin as well as between the amount of pancreatic secretions and serum secretin levels. Pancreatic secretions were decreased markedly in group F and moderately in B. Basal tissue blood flow measured by hydrogen clearance method was low in D, E, and F when compared with that in A.     

Serum gastrin levels in the differential diagnosis of recurrent peptic ulceration due to retained gastric antrum

If recurrent peptic ulceration follows partial gastrectomy with Billroth II reconstruction, retained antrum on the duodenal stump may be the culprit. Moderate hypergastrinemia and a high basal acid output (BAO) to maximal acid output (MAO) ratio on gastric analysis should alert the clinician. Careful filling of the afferent loop on barium meal or technetium 99m scanning may verify the diagnosis. The secretin provocative test may be helpful in distinguishing retained antrum from the Zollinger-Ellison syndrome by eliciting a decrease in serum gastrin levels in patients with retained antrum and an increase in serum gastrin levels in patients with Zollinger-Ellison syndrome.     

Acid and Endocrine Responses to Meals Varying in pH in Normal and Duodenal Ulcer Subjects

Recent studies suggest that duodenal ulcers may develop because of increased drive to secrete acid and decreased effectiveness of feedback mechanisms that inhibit acid output. This study was designed to compare gastric acid, gastrin, gastric inhibitory peptide (GIP) and secretin responses to meals (varying in pH) in 12 normal subjects and nine duodenal ulcer patients. Acid secretion was measured by an intragastric titration method which allows actual measurement of acid response to food within the stomach (ten per cent amino acid meal (AAM) adjusted to various pH levels, 7-1.5). Blood samples were collected at each pH level for radioimmunoassay of gastrin, secretin and GIP. Gastric acid and gastrin responses to AAM were found to be significantly greater in duodenal ulcer patients than in normal subjects. In duodenal ulcer patients, acid response to AAM at pH 7 or 5.5 reached 82% of Histalog maximum. Decreasing the pH of the meal resulted in a stepwise reduction in both acid secretion and gastrin in normal subjects and duodenal ulcer patients. At pH 1.5, acid inhibition was complete, but gastrin inhibition was partial. Secretin increased significantly at pH 1.5; there was no difference in secretin release between the groups. Plasma GIP was highest at pH 7 in all individuals. Use of a marker substance showed 80% recovery of AAM at pH 7-4; below pH 4, recovery rose to about 90%. We conclude that gastric acid and gastrin release are pH-dependent in normal and duodenal ulcer subjects. Inhibition of gastric secretion by acidified meals is associated with a pH-dependent suppession of gastrin and GIP levels and elevation of plasma secretin. This study confirms increased acid and gastrin responses in duodenal ulcer patients but shows no evidence of defective feedback inhibition of gastric secretion and gastrin release.     

Prospective controlled trial of a standardized meal stimulation test in the detection of pancreaticoduodenal endocrine tumours in patients with multiple endocrine neoplasia type 1

BACKGROUND: Use of a standardized meal stimulation test has been recommended for the early diagnosis of pancreaticoduodenal endocrine tumours (PETs) in patients with multiple endocrine neoplasia type 1 (MEN 1). The diagnostic value of this test was re-evaluated. METHODS: In a prospective, controlled trial 58 standardized meal stimulation tests (563 kcal) were performed in 12 patients with MEN 1 and histologically, biochemically and/or radiologically confirmed PETs (group 1), 11 carriers of an MEN 1 mutation with no evidence of PETs (group 2) and in 27 healthy controls (group 3). Serum pancreatic polypeptide (PP) and gastrin concentrations were measured before and during the test meal. RESULTS: Patients in group 1 had significantly higher mean basal serum PP and gastrin concentrations than patients in group 2 and controls (P < 0.05). In all three groups an increase in serum PP was observed after meal stimulation, but there was no significant difference between the groups. No increase in gastrin level was found in any of the groups after meal stimulation. CONCLUSION: The standardized meal stimulation test does not reliably indicate the presence of PETs in patients with MEN 1, whereas raised basal serum PP and gastrin levels do. The expensive and time-consuming meal test can be excluded from MEN 1 screening programmes.     

Long-term effects on the regulation of pancreatic secretion after gastric surgery

BACKGROUND: Apart from smoking, known risk factors for the development of pancreatic carcinoma are few, gastric resection being proposed as one. The trophic effect of cholecystokinin (CCK) on the pancreatic gland is well known from animal experience and increased concentrations of CCK in plasma have been shown to induce pancreatic neoplasia experimentally. In several studies the release of CCK in response to food ingestion has been shown to be increased following gastric surgery. However, in those studies, the time between surgery and investigation of the CCK response was short, and methods of CCK analysis have since improved. PATIENTS AND METHODS: In patients, partially gastrectomized 8 years (median) earlier, we studied the plasma concentrations of CCK, insulin and gastrin, as well as some specific pancreatic enzymes. The findings were compared to an age-matched control group of individuals not subjected to gastric surgery. RESULTS: Basal CCK concentrations in the operated group were found to be lower, but increased postprandially to the same level as in controls. Serum levels of specific pancreatic enzymes were equal in the 2 groups. CONCLUSION: It is possible that a disturbed regulation of pancreatic secretion, or a secretory dysfunction within the gland, following partial gastrectomy, could contribute to the development of pancreatic carcinoma. However, our findings do not favor the idea of plasma CCK as a promotor of pancreatic carcinoma.     

Physiologic significance of the residual stomach after proximal gastrectomy from the view-point of serum gastrin

The physiological significance of the residual distal stomach after proximal gastrectomy (PG) was evaluated in dogs from the view-point of serum gastrin. The fasting gastrin levels in both (1/2 and 2/3) PG groups were high, especially in the 1/2 PG group. The serum gastrin levels did not decrease with time after test meal stimulation in both PG groups. This points to a disturbance of the short loop feedback mechanism in gastric secretion due to a reduction in gastric acid secretion. The elevated gastrin secretion after PG may be beneficial for postoperative digestion and absorption of food. Therefore, it is important when possible, to preserve the distal stomach of operated gastric cancer patients, and to select a reconstructive procedure which permits passage of food through the preserved distal stomach.     

Hyperparathyroidism and hypergastrinemia revisited

The prevalence of hypergastrinemia was determined in 38 consecutive patients with proved primary hyperparathyroidism. Uncorrected serum calcium levels ranged from 2.6 to 4.0 mmol/L and parathyroid hormone levels from 260 to 8750 ng/L (normal less than 600 ng/L). Preoperative serum gastrin levels were grossly elevated (1000 to 4000 ng/L) in three patients (normal median 63 ng/L; range 30 to 120 ng/L). Two patients were achlorhydric. After parathyroidectomy (adenomatous hyperplasia) in the third patient, the serum gastrin level decreased from 4000 to 3000 ng/L, with a negative response to both a secretin challenge and a meal test. The latter patient was subsequently shown to have an adrenal ganglioneuroma and islet cell hyperplasia, neither containing gastrin, and at 4-year follow-up she still has no symptoms from the hypergastrinemia. Eight patients had a modest hypergastrinemia. Serum gastrin levels returned to normal in three of the four patients after parathyroidectomy. The fourth patient had rheumatoid arthritis, which can be associated with hypergastrinemia. The mean plasma gastrin level before operation (100.3 +/- 26.1 ng/L) was similar to the postoperative value (67.0 +/- 18.5 ng/L). There was no correlation between parathyroid hormone and gastrin levels nor between serum calcium and gastrin levels. The three patients with duodenal ulcers did not have elevated gastrin levels. Therefore it would appear that routine screening of patients with primary hyperparathyroidism adds little to their clinical management.     

The effect of small bowel bypass and subsequent resection on gastric acid secretion and serum gastrin

Evaluation of gastric acid secretion and serum gastrin response to proximal or distal intestinal bypass and subsequent resection was undertaken. Ten dogs with gastric fistulas underwent control secretory studies consisting of basal acid output (BAO), maximal vagal stimulation (2 deoxy-d-glucose (2DG) 150 mg/kg iv), maximal histamine stimulation (160 μg/kg/hr iv), and test meal stimuli. Serum gastrin was measured basally and following gastric stimulation. Dogs were then divided into two bypass groups: Group I, distal bypass, leaving 40 cm jejunum and 4 cm ileum; and Group II, proximal bypass, leaving 4 cm jejunum and 40 cm ileum. Postoperatively, repeat studies were performed. Both groups then underwent resection of the bypassed segments followed by repeat secretory and gastrin tests. BAO was significantly increased in Group I dogs. BAO increased from a control of 0.04 ± 0.02 to 0.51 ± 0.19 meq H⁺/60 min (±SEM). No significant changes in BAO were observed in Group II following bypass. Acid secretion to maximal vagal or maximal histamine stimulation was not significantly different in either group. Serum gastrin response was unchanged in either group following a test meal. In Group I dogs, resection of the previously bypassed bowel produced a further significant increase in BAO (1.44 ± 0.4 meq H⁺/60 min). After resection of the bypassed bowel, there was no significant change in basal or stimulated gastrin. Gastric fistula BAO increased following 90% distal but not proximal bypass; subsequent resection of the bypassed segment produced a further increase in BAO. Acid secretory responses to both histamine and 2DG were not influenced by either bypass or resection. An increase in BAO without a change in the background of serum gastrin may suggest the presence of a gastric secretory inhibitor in the distal small bowel.     

Interrelations between serum gastrin levels, gastric emptying and acid output before and after proximal gastric vagotomy and truncal vagotomy and antrectomy.

In a prospective study of proximal gastric vagotomy and truncal vagotomy and antrectomy measurements were made, before and after operation, of acid output, gastrin output and gastric emptying of a solid and a liquid meat extract meal. No relationships were demonstrable between acid output and gastrin output. Truncal vagotomy and antrectomy (TVA) produced rapid early emptying of both meals combined with gross prolongation of the overall emptying of the solid meal. Truncal vagotomy and antrectomy reduced the intergrated gastrin output after either meal. Proximal gastric vagotomy (PGV) produced rapid early emptying of the liquid meal with no alteration in the early emptying of the solid meal; however, overall solid meal emptying was delayed. Proximal gastric vagotomy increased basal, peak and integrated gastrin output. In preoperative patients slow solid meal emptying was associated with higher gastrin output but after PGV the reverse was found, the slowest emptiers having the lowest gastrin output. These findings do not support the contention that a pyloroplasty should be added to PGV to reduce the hypergastrinaemia produced by the operation.     

Results of long follow-up study for peptic ulcer patients treated with gastrectomy

This clinical study was based on 307 peptic ulcer patients treated with gastrectomy over a 15-year period in our department. Numbers of surgical cases for peptic ulcer remarkably decreased after the introduction of cimetidine in 1980. A median age of gastric ulcer patients was in sixth decades, whereas duodenal ulcer in fifth decades. Surgical indications were 60 percent in intractable ulcer, 30 percent in complication as bleeding, stenosis and perforation, and 10 percent in suspicious malignancy. After cimetidine introduction intractable cases decreased from 63 percent to 44 percent. There was no remarkable difference in the fasting and peak plasma secretin concentrations in postprandial period between peptic ulcer patients and normal controls, however, in gastrectomized patients the plasma secretin response decreased in postprandial state. Follow up study was made on a point of postoperative recurrence and postgastrectomy syndrome. Small stomach syndromes such as insufficient food intake and body weight loss were observed in 10 and 30 percent in the gastrectomized patients, but 86 percent of the patients were satisfied with the results of operation. We concluded that gastrectomy for peptic ulcer was treatment of choice from the point of low recurrence rate and no severe postgastrectomy disorders.     

The early diagnosis of gastrinoma.

Despite the increasing awareness of gastrinoma and its lethal peptic ulcer sequelae, the diagnosis is often initially missed or made as a terminal event. The authors screened all patients with peptic ulcer symptoms serious enough to warrant hospital admission or those associated with diarrhea, nephrolithiasis, hypercalcemia, or pituitary abnormality. In a one-year period (1979-1980) nine (of 14 suspected) new gastrinoma patients were identified using a sensitive and specific gastrin radioimmunoassay in combination with provocative tests including IV secretin, calcium, and food. Conventional upper GI series, CAT scan, arteriography, and endoscopy provided no additional information other than to confirm the presence of ulcer disease. Basal plasma gastrin levels were more than 200 pmol L-1 in only three of the nine (normal fasting plasma gastrin levels are less than 25 pmol L-1). Three patients presented with acute¿ulcer perforation, and the diagnosis of gastrinoma was suspected because of multiple ulcers and pancreatic masses. In three other patients, previous duodenal ulcer surgery had failed. One patient with dyspepsia, high basal plasma gastrin, negative secretin and calcium infusion studies, and a positive meal test was diagnosed as having G-cell hyperplasia; this was confirmed by biopsy and antral gastrin extraction. Antrectomy alone resulted in cure. In all patients tested, a positive calcium infusion or secretin bolus (greater than 100% rise over basal) strongly suggested the diagnosis of gastrinoma, which was confirmed at surgery. In the acute perforations, initial management with omental patch and cimetidine therapy allowed survival of two patients, while emergency total gastrectomy in the third resulted in death due to esophagojejunal leak. Elective patients were treated with cimetidine initially for at least two weeks before total gastrectomy. In this group there were no operative mortalities, and postoperative morbidity was minimal. This series illustrates three important points: (1) careful screening of an ulcer population using gastrin radioimmunoassay and provocative tests has enabled a high yield of gastrinomas while conventional investigations are of minimal values; (2) a high index of suspicion in appropriate cases is necessary; and (3) total gastrectomy performed under elective circumstances is safe and allows the patients to resume a normal and healthy life without the sequelae of aggressive peptic ulceration or daily drug administration.     

The Zollinger-Ellison syndrome--23 years later.

The effects of recent diagnostic and therapeutic advances were assessed in 65 patients with the Zollinger-Ellison syndrome (ZES). Twenty-seven patients seen between 1955 and 1970 were compared with 38 patients seen between 1971 and 1977. The earlier patients had a higher incidence of virulent ulcer disease (56% vs. 24%), other endocrinopathies (48% vs. 13%), and malignant gastrinoma (44% vs. 25%). Earlier diagnosis is the result of liberal use of serum gastrin measurements and provocative tests for gastrin release (calcium and secretin), and an increased awareness of this syndrome. Because their basal gastrin values were in a range that overlapped ordinary ulcer disease, 47% of patients encountered in recent years required provocative testing with secretin for diagnosis. If the gastrin concentration falls to normal following resection of a gastrinoma, the tumor has probably been completely removed. In our patients, gastrin measurements after total gastrectomy had no prognostic significance in regards to clinical progression or regression of the neoplasm. Of 12 patients treated with cimetidine, nine experienced symptomatic improvement, and three did not. Resection of the gastrinoma should be attempted if the lesion is solitary and located in the body or tail of the pancreas, or if it is an isolated duodenal lesion. Otherwise, total gastrectomy remains the treatment of choice. In 38 patients, total gastrectomy with Roux-en-Y esophagojejunostomy was followed by 97% survival and minimal difficulties with nutrition or dumping.     

Removal of mesenteric gastrinoma: a case report

A 37-year-old man with a primary mesenteric gastrinoma is reported. A parathyroid adenoma had been removed 13 years ago. Six years earlier the patient underwent an emergency distal gastrectomy because of massive bleeding from a duodenal ulcer. Two months later stomal ulcers developed associated with hypergastrinemia. No gastrinoma was detected and total gastrectomy was performed. The fasting plasma level of gastrin was stable in the range from 580 to 920 pg/ml for the following 5 years. However, the level was found to abruptly increase to 4125 pg/ml. The level increased progressively to 11383 pg/ml within 1 year. A gastrinoma was identified in the jejunal mesenterium, and it was completely removed. After surgery the plasma level of gastrin decreased below the limit of the assay, and the paradoxical response to secretin was no longer observed.     

Postprandial plasma secretin response in various types of reconstructive surgery of the stomach and pancreas

The postprandial plasma secretin concentrations were investigated in patients with Billroth I, Billroth II, Roux-en Y and jejunal interposition following gastrectomy or modified Child's reconstruction after pancreatoduodenectomy. In patients with Billroth I anastomosis the postprandial plasma secretin response was not so high as that for normal volunteers, however it was much better compared with Billroth II anastomosis and Roux-en Y anastomosis after total gastrectomy. In an interposed jejunal anastomosis after total gastrectomy the plasma secretin increased at 20 minutes in postprandial state, even though there was not clear postprandial response of plasma secretin in patients with Roux-en Y anastomosis. Following the modified Child's method after pancreatoduodenectomy the postprandial plasma secretin response was similar to that of Billroth II anastomosis. Following acid load plasma secretin response was much higher than that of postprandial state in patients with Billroth-I, Billroth-II and Roux-Y anastomosis after gastrectomy. The results indicate that acid is important in stimulating secretin release and also the passage of food through the duodenum is important for the release of secretin.     

Serum gastrin and secretin levels after the Exalto-Mann-Williamson procedure.

The Exalto-Mann-Williamson procedure produces peptic ulceration in nearly 100% of experimental animals but the mechanism is unknown. To investigate the possible hormonal role of the gastric acid hypersecretion seen after this procedure, we investigated preoperative and postoperative serum gastrin and secretin concentrations. There was no significant change in serum gastrin; however, serum secretin concentrations increased to 2 1/2 times the preoperatve value, most likely secondary to the enhanced secretion of gastric acid. These data do not suppport the theory that alterations in circulating secretin or gastrin levels are responsible for the gastric acid hypersecretion following the Exalto-Mann-Williamson operation.