Allicin-induced Activation of Peristalsis in Rat Ileum Depends on Bicarbonate Ion Transport

Background: 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, the direct correlation between these two activities remains unclear. Hence, this study investigated the correlation between the allicin-induced activation of peristalsis and ion transport in the rat intestine.Methods: In this work, we used ileal segments of nine-week-old Sprague-Dawley rats, which have more active spontaneous contractions than colonic segments. 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. SPSS software was used for data analysis and P-values 0.05 was considered as significant.Results: A dose of 100 μM allicin induced a significant positive ΔPD when administered to the serosal side of the ileum (P-value for 100 μM vs. 30 μM=0.038). Removing 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 a bicarbonate ion transporter (30 μM 5-nitro-2-(3-phenylpropylamine) benzoic acid).Conclusion: The present study on ion transport suggests that allicin mainly induces the ileal electrogenic secretion of bicarbonate ions in the 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.