Antral Pouches Research Articles

A modified innervated antral pouch preparation.

Gastric motility in the conscious state in dogs has been studied traditionally by intraluminal balloon techniques; extraluminal strain gauge transducers 1-5 and implanted electrodes 6-10 have been used more recently. The latter methods more closely approximate normal physiologic conditions as they involve no intragastric contact or distention, factors which may have a direct or indirect stimulatory effect on motor activity. The balloon techniques, however, have the virtue of simplicity and convenience and require for their execution comparatively inexpensive and easily managed equipment. The gastric preparation ideally suited to simultaneous secretory and motility studies (utilizing a balloon technique) should have two pouches which have both morphologic and physiologic identity with the stomach. Construction of the usual innervated antral pouch, 11-13 however, completely separates the antrum from the proximal portion of the stomach, thus creating an unphysiologic or artificial state. Moreover, reestablishment of gastrointestinal continuity by gastroenterostomy in effect precludes accurate and

Heidenhain pouch response to antral stimulation before and after antral denervation in dogs.

SummaryIn dogs with Heidenhain pouches and vagally innervated antral pouches, denervation of the antral pouch produced the following effects on secretion of acid from the Heidenhain pouches: (a) the responses to submaximal doses of exogenous gastrin extract and to histamine were not significantly changed, (b) the response to 2-deoxy-D-glucose, which presumably acts by vagal release of gastrin, was greatly decreased, and (c) the response to bathing the mucosa of the antral pouch with solutions of acetylcholine or glycine was greatly decreased. The results suggest that tonic vagal impulses facilitate the local release of gastrin by acetylcholine and glycine.

Effect of Gastrin on Gastric Motor Activity

Motility was recorded in 104 experiments on gastric pouches using pressure tracings from air filled balloons. Pentagastrin was administered intravenously either as a constant infusion, 3 μ g per kg per hr, or as a single injection, 1 μ g per kg. Endogenous gastrin was released by perfusion of the isolated antrum with 0.1% acetylcholine, 160 ml per hr. In vagally innervated preparations (innervated antral pouch or gastric fistula) pentagastrin administration caused a sharp increase in frequency and a simultaneous and approximately equal fall in the amplitude of contractions. Thus, the motility index was nearly the same before and after administration of pentapeptide, indicating that gastrin probably does not activate propulsive peristalsis. A mixing function is postulated. In vagally denervated preparations (denervated antral pouch or Heidenhain pouch) intravenous pentagastrin caused the intermittent contractions to become continuous. In denervated antral pouch there was no reduction in contraction pressure. Endogenous gastrin released by acetylcholine perfusion of the isolated antrum caused almost identical changes in motility in both vagally innervated and denervated preparations. Monitoring of gastric secretion indicated pentagastrin dosage used was comparable to the endogenous gastrin released. It appears that the motility effects observed are physiological rather than pharmacological phenomena. Under conditions of this experiment neither intravenous pentagastrin nor endogenous gastrin caused any observable change in gastric tonus, whether in vagally innervated or denervated preparations.

Effect of Antral Acidification on Acid Secretion Induced by Meat and Pentagastrin

The effect of altering the pH of innervated antral pouches on the acid secretory response to either single feeds of ox heart or pentagastrin was studied in 2 dogs with innervated, and 2 dogs with denervated gastric pouches. The outputs of pepsin were also measured following the meals of ox heart. Acidification of the antral pouches inhibited the acid secretory response to ox heart, while alkalinization produced no alteration of results. The outputs of pepsin were not affected by alterations in the pH of the innervated antral pouches. Acidification of the innervated antral pouches did not alter the outputs of acid from denervated fundic pouches in response to sequential doses of pentagastrin but produced an inhibition in the response to submaximal doses from the innervated fundic pouches. The results do not support the existence of an antral inhibitory hormone, and suggest that an inhibitory mechanism is present when the intrinsic nerve pathways are intact.

Effect of Gastrin and SC 15396 on Gastric Motility in Dogs

A continuous infusion of porcine gastrin preparations, including crude gastrin, gastrin I, or gastrin II, in doses submaximal for gastric acid secretion, stimulated rhythmic antral contractions in the intact stomach or innervated antral pouch of dogs. SC 15396 markedly decreased gastrin-stimulated gastric acid secretion, but had no effect on gastrin-stimulated antral motility. Provided that the endogenous release of gastrin can be shown to produce an effect similar to exogenous gastrin, stimulation of rhythmic antral contractions should be included as one of the physiological actions of gastrin.

The effect of gastric antral stimulation upon the secretion of hepatic bile.

SummarySeven dogs were prepared with completely separated vagally denervated antral pouches, gastrojejunostomy, and cholecystectomy. A duodenal cannula was placed opposite the opening of the common bile duct in each animal. In 3 of these dogs, a Heidenhain pouch was also constructed whereas in the other 4 animals a gastric cannula was placed in the ventral wall of the stomach. Biliary volume and composition were studied by catheterization of the common bile duct during constant i.v. infusion of 2% sodium taurocholate to maintain an intact enterohepatic circulation of bile salts. In the dogs with Heidenhain pouches or when the gastric cannula was closed, perfusion of the antral pouch with buffered 4% choline chloride solution at pH 7.5, caused highly significant increases in biliary volume, HCO3 concentration and output, Cl concentration and output and total outputs of Na, K, bile salts, and bile solids. The concentration of Na and K was unchanged but the concentration of bile salts and solids was decrease...

Some factors influencing the stimulatory effect of ethanol on gastric aicd secretion during antrum application.

AbstractVariations in gastric secretory response to antral application of ethanol were studied in Heidenhain and Pavlov pouch dogs with isolated, innervated antral pouch, to disclose the influence of instillation pressure, temperature, concentration, pH and ion composition. Secretory response increased in 2 of 5 dogs and remained unchanged in 3 dogs during rise of installation pressure from 0 cm H2O to 20–30 cm H2O. Secretory responses were essentially alike, whether alcohol solutions were administered at room temperature or at body temperature. Threshold stimulatory concentration was 2–4% (v/v), optimal effect occurred at 8–16%, a decrease was usually observed at 32%. Antrum pouches were perfused with buffered ethanol solutions at pH values between 7.0 and 1.0. No significant difference of the stimulatory effect was noted within the pH range 7.0–3.0. At pH 2.0 the stimulatory action was decreased by about 40% and at pH 1.0 almost totally suppressed. The slope of the pH curve seems to be independent of the ethanol concentration. The pH curves for the stimulatory effect of alcohol in the antrum and for vagus stimulation are almost identical. The ethanol effect was inhibited by high concentrations of K+ and Ca++ but uneffected by corresponding concentrations of Na+ and Mg++.

Stimulation of gastric acid secretion by irrigation of the antrum with some aliphatic alcohols.

AbstractEthyl alcohol is known to stimulate gastric acid secretion in fundic pouch dogs during irrigation of the antrum. A comparison was made with regard to such an effect of a series of aliphatic alcohols including methyl, ethyl, n‐propyl, isopropyl, n‐butyl, isobutyl, sec‐butyl and tert‐butyl alcohol. Dogs provided with a Heidenhain or a Pavlov pouch and isolated, innervated antral pouch were used. The only alcohol besides ethanol that showed a potent stimulatory effect was n‐propyl alcohol. All other alcohols tested had an effect less than half of that of ethanol. A change from one stimulatory alcohol to the corresponding isocompound caused a marked decrease of the effect. Isopropyl alcohol, one of the “non‐stimulatory” aliphatic alcohols, did neither show a synergistic nor an inhibitory action on the effect of ethyl alcohol or n‐propyl alcohol during simultaneous administration, indicating almost no interference with gastrin release mechanisms. n‐Propyl alcohol together with ethyl alcohol showed a dose‐response related action. Methyl alcohol was almost inactive. The results indicate that the stimulatory effect of alcohols could not be related to water or fat solubility but to the molecular configuration.

The effects of antral acidification on the gastric secretion stimulated by endogenous and exogenous gastrin.

1. In conscious dogs with Heidenhain fundic pouches and denervated antral pouches control dose-response curves to gastrin pentapeptide or methacholine were constructed, both when the antral pouch was empty and when it was stimulated with ACh (0.5 g/100 ml.) in citrate buffer adjusted to pH 5.5 or 1.5.2. When the antral pouches were irrigated with ACh (0.5 g/100 ml.) at pH 1.5 the acid outputs from the Heidenhain pouch in response to graded doses of gastrin pentapeptide or methacholine were significantly less at each dose level than those obtained with ACh at pH 5.5.3. The acid outputs from the Heidenhain pouch in response to either pentapeptide or methacholine with or without antral irrigation with ACh at pH 1.5 were approximately equal. Therefore the difference between the dose-response curves obtained by stimulation with ACh at pH 5.5 and those obtained by stimulation with ACh at pH 1.5 represents gastrin release rather than release of an inhibitory hormone.4. The pepsin outputs from the Heidenhain pouch during antral irrigation with ACh at pH 1.5 were significantly less than those obtained with ACh at pH 5.5 at each dose of methacholine.5. The maximal pepsin output was significantly greater in response to methacholine than to gastrin pentapeptide.6. Gastrin pentapeptide was not a significant stimulant of pepsin secretion from the Heidenhain pouch.7. The intestinal phase of parietal secretion was not inhibited by bathing the separated antrum with acid.

Pancreatic secretion stimulated by the action of alcohol on the gastric antrum.

Perfusion of an antral pouch with ethanol increased the pancreatic volume and enzyme content after a 10–30 min. latent period. Gastric secretion also increased in each experiment, but after a 30–40 min. latent period.

Recent advances in the physiology of gastrin.

On 18 May 1905 there was presented at a meeting of this Society a paper in the name of John Sydney Edkins entitled ‘On the chemical mechanism of gastric secretion’ (Edkins 1905). It described experiments in which simple aqueous extracts of antral and fundic mucosa were tested for their power to stimulate gastric secretion when injected as single intravenous doses into anaesthetized cats. Antral extracts excited a secretion of acid and pepsin; fundic extracts did not. Edkins concluded that certain cells in the antral mucosa contained a principle which he named ‘gastrin’; this, he considered, entered the circulation during gastric digestion and stimulated the fundic glands to further activity following on the initial vagal reflex excited by the eating of the meal. These experiments, later recounted in detail (Edkins 1906) initiated more than 40 years of controversy as to the existence of a gastric antral hormone. When attempts were made to confirm and extend Edkins’s observations it was soon discovered that a stimulant of gastric acid secretion could be found not only in antral mucosa but also in many other tissues; and when eventually this ubiquitous agent was identified as histamine (Barger & Dale 1910; Dale & Laidlaw 1910; Popielski 1919) it was widely concluded that the activity of Edkins’s antral extract was due to the presence in it of this substance. The situation was further confused by the failure of apparently well-designed attempts to prove by physio­logical experiment that an antral hormonal mechanism existed, whatever the nature of the hormone. For example, Ivy & Whitlow (1922) and Priestley & Mann (1932) provided dogs with fundic and antral pouches and irrigated the latter with solutions regarded at the time as likely to cause a release of the hormone; but no response from the fundic pouch could be detected, and many years elapsed before the probable reason for such failure became appreciated.

Choleresis Induced by Stimulation of the Gastric Antrum

Summary The volume and composition of bile were studied by cannulation of the common bile duct through a duodenal fistula in dogs with separated antral pouches, cholecystectomy, and either total gastrectomy with Heidenhain pouch or gastrojejunostomy with gastric fistulas. Perfusion of the antral pouch with buffered acetylcholine solution at pH 7.0 caused a choleresis characterized by increased bicarbonate concentration and output, as well as increased gastric acid secretion. These effects were not seen during antral perfusion with acetylcholine chloride solution acidified to pH 1.0. These studies indicate that the antral mucosa is the source of a choleresic substance, and they are consistent with the hypothesis that this substance is gastrin.

Regulation of secretion of mucus from the gastric antrum.

SummaryGastric secretion of mucus was studied in dogs by collecting secretions from vagally‐denervated or ‐innervated gastric antral pouches. Mucous secretions were studied for volume and for concentration of nitrogen, hexsoses, hexsosamines, L‐fucose and sialic acid concentrations in dialyzed, lyophilized mucosubstance. Gastric mucosal content of mucus of rats was measured by analyzing the concentration of hexsosamine and sialic acid in freeze‐dried gastric mucosal scrapings. Vagal stimulation of the gastric antrum and administration of cholinomime‐tic agents had no detectable influence on either the volume or the biochemical composition of antral mucus. Insulin‐induced hypoglycemia appeared to depress the secretion of mucus. Adrenergic stimulation was without influence. Serotonin had a strong stimulatory effect on the volume of mucus secretion but did not alter its biochemical composition. Cortisone had a profound inhibitory influence on the secretion of mucus and altered its biochemical composition by decreasing the concentration of sialic acid. Parathyroid extract was found to increase gastric mucosal content of mucus in rats.

Studies on a Gastric inhibitory Substance Isolated from Juice of the Gastric Antrum in the Dog.

Six mongrel dogs were prepared with vagally denervated antral pouches and Heidenhain fundic poucnes. An extract was prepared from juice secreted by the antrum by dialyzing against water and lyophilization. This gastric inhibitory substance (GIS) was assayed in the dog from which it was prepared. Three types of gastric secretion were studied: histamine-stimulated (50-200 µg per hour i.v.), gastrin-stimulated (1-3 mg per hour i.v.), and the response to a test meal consisting of 200 g strained beef liver homogenate. GIS injected in doses of I mg/kg body weight in a single i.v. dose reduced gastric acid secretion by 50-75 per cent. The gastric secretion of pepsin was not significantly altered by the injection of GIS. No severe side reactions were observed after the injection of GIS, except an elevation of body temperature. However, the relation between body temperature and inhibition was probably different from that encountered by others utilizing bacterial pyrogen.

Effect of Denervation and Subsequent Resection of Antral Pouches on Secretion from Heidenhain Pouches in Response to Gastrin and Histamine

Effect of Denervation and Subsequent Resection of Antral Pouches on Secretion from Heidenhain Pouches in Response to Gastrin and Histamine

Studies of the humoral control of gastric secretion in dogs with autogenous and homotransplanted antral and fundic pouches

Studies of the humoral control of gastric secretion in dogs with autogenous and homotransplanted antral and fundic pouches

The Effect of Antral Acidification on the Intestinal Phase of Gastric Secretion in the Heidenhain Pouch Dog

Nyhus, L. M., M. J. Rheault and L. S. Semb. The effect of antral acidification on the intestinal phase of gastric secretion in the Heidenhain pouch dog. Acta physiol. scand. 1965. 65. 11–19. — Five dogs were prepared with vagally denervated antral pouches and Heidenhain fundic pouches. As a stimulus for the intestinal phase of gastric secretion a test meal was given, consisting of 200 g strained beef liver. The acid response from the Heidenhain pouch was determined in each dog in half-hour samples for 4 hrs after the meal. In each dog, the following experiments were carried out: I: Test meal, no perfusion of antrum 25 expts. in 5 dogs II: Test meal, perfusion of antrum with 0.9 % saline 25 expts. in 5 dogs III: Test meal, perfusion of antrum with 0.1 N HCl 25 expts. in 5 dogs IV: No test meal, perfusion of antrum with 0.9 % saline 10 expts. in 4 dogs There was a highly significant greater average acid response to the test meal when the antrum was perfused with saline (II) as compared to the response when the antrum was acidified (III) (p = 0.00004) or not perfused at all (I) (O = 0.008). There was, however, no significant difference in the average acid outputs of expts. I and III (p = 0.059) in 4 dogs, the fifth showed a greater output (p = 0.040) when thc antrum was acidified. When no test meal was fed to the dogs, and the antrum perfused with saline, there was a release of endogenous gastrin from the antrum, as indicated by a measureable secretion from the Heidenhain pouches. The results are discussed, and the conclusion is drawn that the results do not support the presence of an antral chalone, but seem to support the theory that antral acidification has an inhibitory effect on release of gastrin.

POTENTIATION OF SHAM FEEDING RESPONSE IN PAVLOV POUCH DOGS BY SUBTHRESHOLD AMOUNTS OF GASTRIN WITH AND WITHOUT ACIDIFICATION OF DENERVATED ANTRUM.

AbstractThe sham feeding response of Pavlov pouch dogs, in which gastrin release had been suppressed by total denervation or resection of the antrum, was augmented 4–21 times by i.v. injection of subthreshold amounts of gastrin demonstrating that subthreshold amounts of gastrin potentiated the effect of vagal stimulation of the HCl glands. The sham feeding responses with or without potentation by subthreshold amounts of exogenous gastrin were not inhibited by acidification of totally denervated antral pouches, suggesting that the hypothetical antral chalone does not interfere at the parietal cell level with the cephalic phase of gastric acid secretion.

Significance of Vagal Release of Gastrin During the Nervous Phase of Gastric Secretion in Dogs

Summary The acid secretory response to sham feeding in Pavlov pouch dogs increased by several hundred per cent following antrumduodenum exclusion. Since pylorotomy did not essentially affect the augmented postexclusion response, regurgitation of duodenal contents into the excluded antrum could not have been an appreciable contributory stimulus. Antral denervation abolished the hypersecretion. On concurrent mechanical stimulation of a denervated antral pouch there was a manifold increase of the sham feeding response, whereas mechanical stimulation of the denervated antrum alone resulted in a liminal or moderate secretion. It is concluded that (1) synergism exists between gastrin and the physiologic vagal excitation of the acid-secreting glands, that (2) vagal release of gastrin from the antrum may cause a manifold increase of the acid secretory response during the nervous phase. The secretory response to insulin hypoglycemia and to sham feeding were determined in the same dogs after the operative measures. The findings demonstrate that the two stimuli in the presence of the antrum similarly reflect the nervous phase of gastric acid secretion. A method for localization of the antrumcorpus boundary during operation is described.

Inhibition of cephalic and antral phases of gastric secretion by antral chalone.

The effect of antral acidification on the antral and cephalic phases of gastric secretion has been studied. Cross-transfusions were carried out between pairs of dogs in which blood from the portal vein of one dog was administered to another dog with a denervated fundic pouch. Transfusion of blood collected during acidification of the antrum resulted in a diminution of Heidenhain pouch acid secretion in response to food and to topical acetylcholine of 64% and 83%, respectively. The effect of antral acidification on gastric secretion stimulated by insulin hypoglycemia was studied in dogs prepared with Pavlov and isolated antral pouches (innervated and denervated). Irrigation of the antral pouch with .1 n hydrochloric acid resulted in a 92% decrease in Pavlov pouch acid output.