Effect of Pentagastrin upon Movements of Water, Electrolytes and Glucose across the Human Jejunum and Ileum

Abstract

The intestinal perfusion technique was used in 10 healthy subjects to measure the effects of pentagastrin (PG) on jejunal and ileal net and unidirectional movements from two isotonic solutions, one of which was glucose-free (solution I) and the other contained 30 mM glucose (solution II); in five further subjects, the effect of the pentapeptide on intrajejunal transit time was assessed, (a) In the jejunum, PG had no effect on net movements of water and electrolytes from solution I, whereas it significantly reduced net absorption of water, sodium, potassium and chloride from solution II, without affecting the absorption of glucose itself, (b) Both jejunal unidirectional fluxes of water, sodium and potassium were reduced by pentagastrin, whatever the solution infused; but, in the presence of glucose, the insorption (lumen to blood flux) of water and electrolytes was predominantly decreased, (c) PG did not modify intrajejunal transit time of fluid, (d) Ileal transport of water and ions was not affected by PG. The mechanism of the action of PG is discussed in the light of current knowledge of transport mechanisms across the intestine, and the possibility is raised that it may act through a reduction of the size of the ‘pores’ of the plasma membrane of the enterocyte. Finally, it is suggested that overproduction of gastrin, as seen in the Zollinger-Ellison syndrome, may play a direct role in the watery diarrhea sometimes observed in this disease.

Synthetic human gastrin I and gastrin-like pentapeptide in studies of intestinal absorption in man

“…Moshal et al [ 17] having used a similar three-lumen perfusion technique and concentration of glucose to ours, also, however, did not find an inhibition of net water, electrolytes and glucose absorption by PG in the proximal human jejunum. The fact that in the study of Modigliani et al [15,16] PG and S H G I had no significant effect on net movements of water and electrolytes from a glucose-free solution, and did not significantly reduce glucose absorption, seems to exclude the possibility that the controversial results might solely arise from the use of higher concentrations of sugar.…”

“…administration of PG in dog experiments as well as decreased net absorption of water, sodium and glucose in the jejunum of patients with Zollinger-Ellison syndrome. Modigliani et al [15,16], using PG and SHG I, found tNat only glucose-stimulated water and electrolyte transport was reduced in human jejunum, not the absorption from a glucose-free solution. In this study PG did not modify intrajejunal fluid transit time.…”

Effect of Pentagastrin, Secretin and Cholecystokinin on Intestinal Water and Sodium Absorption in the Rat

“…The effects of other hormones vary with animal species, methods, doses and intestinal sites. Gastrin was found to decrease absorption of water and Na in canine jejunum and ileum (1,5) but in man the decreased absorption early observed (21) was found to occur at the jejunal level in the presence of glucose only (20) or not to occur at all (8). Secretin decreased the ileal absorption and induced a jejunal secretion in rat (14) and man (18) but flash injection or infusion did not induce any effect in rat (3), dog (1) and man (19).…”