S. E. Svensson

The role of the antrum and the vagus nerve in the formation of gastric mucosal histamine

1. The effects of the vagus nerve and of antral gastrin on the rate of histamine formation (histamine forming capacity, HFC, i.e. histidine decarboxylase activity) in the parietal cell region of the gastric mucosa has been investigated in the following stomach preparations: gastric fistula, denervated Heidenhain pouch, antral resection with gastrojejunostomy, gastrojejunostomy with exclusion of the duodenum and in the intact stomach. The determinations of mucosal HFC were made on fasting rats and on re‐fed animals when the effect of feeding was studied.

Inhibition of gastric secretion by atropine in conscious rats

1. The effect of atropine on acid and pepsin secretion, stimulated by feeding, vagus excitation or infusions of gastrin, histamine and methacholine, was studied in conscious rats provided with a Pavlov or a Heidenhain pouch.

IMPLICATION OF GASTRIC MUCOSAL HISTAMINE IN INHIBITION BY ISOPRENALINE OF PENTAGASTRIN‐INDUCED GASTRIC SECRETION

1 The effect of isoprenaline on pentagastrin‐induced gastric secretion was studied in conscious rats with Heidenhain pouches. The influence of isoprenaline on pentagastrin‐induced release and formation of gastric mucosal histamine was also examined. 2 Isoprenaline strongly inhibited pentagastrin‐induced acid secretion, an inhibition which could not be overcome by increasing the dose of pentagastrin. 3 Propranolol blocked the inhibitory effect of isoprenaline on pentagastrin‐induced acid secretion. 4 Isoprenaline enhanced pepsin secretion induced by pentagastrin, an effect which was blocked by propranolol. 5 Isoprenaline reduced the increase in formation and release of gastric mucosal histamine following pentagastrin infusion, an inhibitory influence which was almost completely blocked by propranolol. 6 The inhibition by isoprenaline of pentagastrin‐induced acid secretion is tentatively related to alterations in gastric mucosal histamine occurring simultaneously.

Gastric secretion and its facilitation as related to gastric mucosal histamine

1. In conscious rats provided with Pavlov or Heidenhain pouches the acid and pepsin responses to vagal stimulation, or infusions of gastrin, histamine, methacholine, and to various combinations of these stimulants have been established. The concomitant mobilization and increased formation of gastric mucosal histamine have also been examined.

Histamine formation in rat gastric mucosa and lung after injecting reserpine or adrenaline

1 . In rats the effect of reserpine, adrenaline and gastrin on the histamine forming capacity (HFC) of gastric mucosa and lung was examined. 2 . Intraperitoneal reserpine as well as subcutaneous adrenaline produced a great increase in HFC of gastric mucosa but a great decrease in HFC of lung. After reserpine the HFC of lung was almost abolished. 3 . As the HFC changes produced by reserpine occurred also after demedullation of the suprarenale—the changes in the mucosa were in fact accentuated—release of the medullary hormones by the reserpine does not account for these changes. 4 . Subcutaneous gastrin caused a great increase in HFC of the gastric mucosa but did not affect the HFC in lung. 5 . The possible role of release of gastrin and corticosteroids for the reserpine‐induced HFC changes is discussed because it is known that reserpine releases gastrin and corticosteroids and that cortisone produces HFC changes in gastric mucosa and lung.

Alterations in histamine metabolism of rat gastric mucosa following vagotomy

1. In female rats subjected to truncal vagotomy with pyloroplasty, pyloroplasty alone or sham operation, the behaviour of gastric mucosal histamine was investigated combining in vivo and in vitro methods.

FURTHER STUDIES ON THE MODE OF ACTION OF ISOPRENALINE ON GASTRIC SECRETION IN THE CONSCIOUS RAT

1 The effect of isoprenaline on gastric secretion evoked by various means has been studied in conscious rats provided with Pavlov and Heidenhain pouches. 2 Interdigestive acid secretion in the Pavlov pouch was reduced by isoprenaline, whereas pepsin secretion was unaltered. 3 Central vagal stimulation effected by 2‐deoxy‐d‐glucose injection evoked a gastric secretory response that was substantially reduced by isoprenaline. 4 2‐Deoxy‐d‐glucose increased the mobilization of gastric mucosal histamine, an effect that was prevented by isoprenaline. 5 Isoprenaline infusion alone induced a slight increase in histamine mobilization and also a considerable elevation of immunoreactive serum gastrin concentration. 6 The secretory response to food in the Pavlov pouch was almost abolished by isoprenaline. 7 Although the acid response to histamine in the Heidenhain pouch was susceptible to isoprenaline inhibition, that to methacholine was not. 8 Pepsin secretion in the Heidenhain pouch preparation stimulated by histamine or methacholine seemed to be enhanced by isoprenaline.

Inhibitory and stimulatory effects of secretin on gastric secretion in conscious rats.

1 . The effect of pure secretin on gastrin‐induced secretion has been studied in conscious rats with Pavlov or Heidenhain pouches. 2 . Rapid intravenous injection of secretin did not inhibit a plateau secretion of acid in the Heidenhain pouch, but infusion of the same amount of secretin over two hours inhibited secretion in both Heidenhain and Pavlov pouches. 3 . A rapid intravenous injection of secretin before the onset of gastrin infusion enhanced the acid secretory response to gastrin in both types of pouches. 4 . Secretin stimulated pepsin secretion.

Gastrin derivatives investigated for secretory potency and for changes in gastric mucosal histamine formation

1 . Acid secretion and rate of histamine formation in the gastric mucosa were determined in rats after injection of hog gastrin II, gastrin pentapeptide and some substituted analogues of the C‐terminal tetrapeptide of gastrin. 2 . Accelerated mucosal histamine formation was induced by hog gastrin II, gastrin pentapeptide and those analogues which elicited acid secretion, whereas secretorily inactive derivatives did not alter histamine formation.