Allicin-induced activation of peristalsis in rat ileum depends on bicarbonate ion transport

Allicin, a main component of garlic, possesses various beneficial pharmacological and therapeutic properties, including anticarcinogenic, bactericidal, and intestinal regulatory effects. Although it is known to regulate intestinal contraction and ion transport, its direct correlation remains unclear. In this study, we investigated the correlation between the allicin-induced activation of peristalsis and ion transport in the rat intestine.We used the ileal segment, which has more active spontaneous contractions than the colonic segment. To examine the role of allicin in regulating electrogenic ion transport in the rat ileum, we measured the transmural potential difference (ΔPD) with an Ussing chamber system. To study intestinal peristalsis, we performed an experiment to measure the velocity of the movement of an artificial pellet during intestinal peristalsis by recording videos with an overhead camera.A dose of 100 μM Allicin induced a significant positive ΔPD when administered to the serosal side of the ileum. The removal of chloride ions from the incubation solution did not significantly change the allicin-induced positive ΔPD. Removing bicarbonate ions from the incubating solution completely suppressed the allicin-induced increase in ΔPD. Allicin-induced pellet movement in the ileum significantly diminished when bicarbonate ions were removed from the incubation solution. Allicin-induced ileal spontaneous peristalsis was completely suppressed in the presence of an inhibitor of bicarbonate ion transporter, 30μM 5-Nitro-2-(3-phenylpropylamine) benzoic acid (NPPB).The present study on ion transport suggests that allicin mainly induces the electrogenic secretion of bicarbonate ions in rat ileum. In addition, a study of intestinal peristalsis suggested that allicin-induced ileal peristalsis depends on the extracellular bicarbonate ions electrogenically secreted in the ileum.