D. Andersen

Effect of dopamine on pentagastrin-stimulated gastric antral motility in dogs with gastric fistula.

The purpose of the present study was to evaluate the effect of dopamine on gastric antral motility in conscious dogs with gastric fistula by using miniature strain-gauge transducers. Infusion of pentagastrin changed the contractile activity to a digestive state. Dopamine, an endogenous catecholamine, was used alone and in conjunction with selective blockade or adrenergic and dopaminergic receptors. The stimulated antral motility was inhibited by dopamine. The effect was significantly blocked by the peripherally acting dopaminergic blocker domperidone and by cis-flupenthixol, which blocks both peripheral and central dopaminergic receptors. The effect of dopamine was not significantly altered by the beta 1-adrenoceptor blocker practolol, the alpha-adrenoceptor blocker phentolamine, or the alpha + beta-adrenoceptor blocker labetalol. Consequently, this study indicates that dopamine acts on gastric antral motility through dopaminergic receptors. beta-Adrenergic receptors, which are active in the impairment of gastric acid secretion, seem not to be involved in the motility response.

Effect of Somatostatin on Bethanechol-Stimulated Gastric Acid Secretion and Gastric Antral Motility in Dogs with Gastric Fistula

The purpose of the present study was to evaluate the effect of somatostatin on gastric acid secretion and gastric antral motility in conscious dogs with gastric fistula. Infusion of bethanechol stimulated dose-dependently acid secretion, whereas the frequency and strength of antral motility was maintained at a high level. Somatostatin inhibited dose-dependently the stimulated acid secretion, whereas the effect on antral motility was more complex, acting especially on the amplitude of the contractions. The effects of somatostatin were not altered by using alpha-adrenergic, beta-adrenergic, dopaminergic, and serotonergic blocking drugs. The dose-response kinetics with four doses of bethanechol with and without somatostatin showed inhibition of a non-competitive type for gastric acid secretion and of a competitive type for antral motility with regard to amplitude.

Effect of Dopamine on Pentagastrin-Stimulated Gastric Acid Secretion and Mucosal Blood Flow in Dogs with Gastric Fistula

The purpose of this study was to elucidate the effect of intravenously administered dopamine on dopamine receptors and adrenergic receptors in terms of its effect on gastric acid secretion, the kinetic mechanism, blood flow, and antral motility. Dopamine was used alone and in conjunction with selective blockade of alpha-, beta-, and dopaminergic receptors. A significant inhibition of gastric acid secretion was found with the highest dose of dopamine used (40 micrograms/kg/min). The kinetic study showed characteristics of a non-competitive type. The anti-secretory effect dopamine was significantly blocked by non-selective beta-blockade or by selective beta-blockade but not by alpha- or dopaminergic receptor blockade. This suggests that the inhibitory effect of dopamine on gastric secretion is mediated by beta-receptors. There was no significant effect on gastric mucosal blood flow, but the ratio between blood flow and acid secretion was significantly elevated during dopamine infusion, indicating that the acid inhibition was not secondary to changes in blood flow. It is concluded that the dopamine inhibition of acid secretion is mediated by beta 1-receptors, unlike the effect on antral gastric motility, which is mediated by dopamine receptors.

Acid Response to Sham Feeding as a Test for Completeness of Vagotomy

The reproducibility of acid responses to modified sham feeding by the chew-and-spit technique (PAOsh) was investigated in 21 duodenal ulcer (DU) patients 8 to 14 days after vagotomy. Possible relationships between PAOsh and the acid response to 0.2 U of insulin per kilogram body weight were examined (PAOI) in 23 other DU patients 8 to 14 days after vagotomy. PAOsh was reproducible to a high degree (PSpearman less than 0.001, CV 2.9%), and a highly significant relationship was found between PAOsh and PAOI after vagotomy (PSp less than 0.001). PAOsh and PAOI were similar when PAOI was low, whereas a highly incomplete vagotomy according to PAOI was followed by a somewhat lower, but substantial, acid response to sham feeding. The relationship between PAOsh and PAOI permits the recommendation of modified sham feeding as a safe stimulant of acid secretion in quantitative testing of completeness of vagotomy.

Effect of Isoprenaline on Pentagastrin-Stimulated Gastric Acid Secretion in Dogs with Gastric Fistula

The purpose of this study was to elucidate the effect of a beta 1-adrenoceptor agonist on gastric acid secretion in conscious dogs with gastric fistula. Isoprenaline, a beta 1- and beta 2-agonist was used alone and in conjunction with selective blockade of beta 2- and beta 1-receptors. Isoprenaline dose-dependently inhibited the secretory volume and the acidity. The antisecretory effect of isoprenaline was significantly blocked by the beta 1-adrenoceptor blocker practolol and by the beta 1 + beta 2-adrenoceptor blocker propranolol but not by H 35/25, a beta 2-adrenoceptor blocker. This indicates that isoprenaline acts on the acid secretion exclusively through beta 1-receptors. Dose-response experiments with five logarithmically increased doses of pentagastrin and one dose of isoprenaline showed unchanged calculated maximum response and an increase in half-maximum acid response. It is concluded that the inhibitory effect of isoprenaline on gastric acid secretion is of competitive or uncompetitive type.

The Antrum in Duodenal Ulcer Patients: Relationship between Antrum Size, Nerve of Latarjet, Gastrin Cell Quantity, and Gastric Acid Secretion

Estimates of the border between antral and fundic mucosa, antral size, antral G-cell density, G-cell population, and total G-cell volume were made from multiple biopsies taken from the gastric curves during parietal cell vagotomy for duodenal ulcer in 33 patients. No relation was found between the landmarks of Latarjets nerve and the border. The fundic mucosa was underdenervated in 20% of the patients, and the postoperative acid response to sham feeding in these was higher than in patients with an overdenervated or optimally denervated border. No relation was found between antral size, defined as antral mucosal volume containing G-cells, and preoperative acid secretion. However, an inverse relation was found between antral size, defined as antral mucosal volume containing no parietal cells, and preoperative maximum acid secretion, suggesting an inverse relation between areas with and without parietal cells. No relation was found between acid secretion and G-cell densities, G-cell population, or total G-cell volume.

Gastric acid response to sham feeding and pentagastrin before and after parietal cell vagotomy in patients with duodenal ulcer.

The influence of sham feeding (PAOSh) preceding pentagastrin-stimulated gastric acid secretion (PAOPg) was investigated in 28 patients with duodenal ulcer (DU) before vagotomy and in 36 after parietal cell vagotomy (PCV). Sham feeding had little influence on PAOPg, and it is concluded that the two secretion tests may be combined. The ratio PAOSh/PAOPg was significantly reduced by PCV. Fourty-four patients with DU were studied for 1 year after PCV, and their PAOPg was measured preoperatively and their PAOPg and PAOSh postoperatively. Seven of the 44 patients had recurrent ulcer within 1 year. PAOPg had no predictive value pre- and post-operatively, but postoperative PAOSh and PAOSh/PAOPg were both significantly higher in patients with recurrent ulcer. It is concluded that PAOSh and PAOSh/PAOPg after PCV may assess completeness of vagotomy, but the relationship between PAOSh and risk of recurrent ulcer may be stronger than that between PAOSh/PAOPg and recurrence.

Prevention of Ulcer Recurrence —Medical vs Surgical Treatment. The Surgeon's View

The need for surgical intervention in duodenal ulcer disease will undoubtedly decrease in the years to come. Occasional failure of medical treatment and persistent doubts about the long-term safety of anti-ulcer drugs will continue to make operation the treatment of choice for some patients, however. Long-term medical treatment and surgery can be considered equally acceptable options for most patients. When operation is considered necessary, parietal cell vagotomy fits the requirements of a modern surgical method better than other techniques. The effective medical treatment now available makes postoperative recurrence of ulcer less important than before and lack of postoperative symptoms has replaced fear of recurrent ulceration as the main concern in the value judgement of both doctors and patients.

Effect of somatostatin on bethanechol-stimulated gastric pepsin secretion in gastric fistula dogs.

The effect of somatostatin on pepsin secretion was determined in six dogs with gastric fistulas during stimulation with bethanechol. Somatostatin inhibited dose-dependently the stimulated pepsin secretion, with a dose of 0.3 micrograms/kg/h being 35% inhibitory during stimulation with bethanechol, 80 micrograms/kg/h. Continuous infusion of somatostatin for 3 h did not cause any signs of tachyphylaxis. Withdrawal of somatostatin produced a return to the control level. The dose-response kinetics with five doses of bethanechol with and without somatostatin showed inhibition of a noncompetitive type. The effects of somatostatin were not altered by using adrenergic, dopaminergic, or serotonergic blocking drugs.

Scintigraphic Localization of Intermittent Gastrointestinal Haemorrhage with Indium-111-Labelled Platelets

Because of the central role of blood platelets in haemostasis, 111In-labelled platelets might be supposed to participate in the haemostatic process and give rise to scintigraphic hot spots at the bleeding sites in cases of intermittent gastrointestinal haemorrhage. Three patients with intermittent gastrointestinal haemorrhage are described in whom focal tracer accumulations after injection of autologous 111In-labelled platelets indicated the presence of transient gastrointestinal haemorrhage. Repeatedly performed scintigraphy after injection of 111In-labelled platelets may prove to be a useful tool for the localization of intermittent gastrointestinal haemorrhage.