Interleukin-8 enhances tetragastrin-stimulated acid secretion in vivo

Recent studies have demonstrated a relationship between cytokines and gastric acid secretion. However, details of the mechanism underlying that relationship have not been elucidated. For this study, an in vivo experiment was undertaken to investigate the possibility that IL-8 would be involved in the mechanism of gastric acid secretion. Gastric lumen-perfused rats were prepared and the stomachs were perfused with a saline solution. The effluent was collected at 15-min intervals and assayed for titratable acid against 0.01 M NaOH. IL-8 (200 ng/rat) given intravenously did not influence basal acid output in rats. However, when IL-8 was administered by injection during continuous tetragastrin infusion (4 microg/kg/hr) acid output increased significantly (P < 0.01). The acid output during the first hour following IL-8 injection was 43.6% higher than prior to the injection. Acid output during the second hour was lower than during the first hour. However, successive injection of IL-8 again increased tetragastrin-stimulated acid output by 23.4% (P < 0.05). IL-8 injection did not change histamine-stimulated acid output. The results indicate that IL-8 has the effect of enhancing gastrin-stimulated acid secretion and might have an important role in the pathophysiology of gastric acid secretion in vivo.