Abstract

Vanillin consumption is common within the global population, often as a flavoring agent. Many vanillin-containing drinks claim a soothing effect on the body as a whole with some reports on their benefit in reducing gastrointestinal (GI) upset. In this study, vanillin was investigated for its ability to reduce rat ileal smooth muscle contractility induced by acetylcholine (Ach) and potassium chloride (KCl). A section of rat ileum was suspended in an organ bath containing Tyrode’s solution. The tissue was stimulated using Ach or KCl and kept under 1 g tension at 37°C while continuously gassing with oxygen. Ileal smooth muscle contractility was studied in the absence and presence of vanillin. The results illustrated that vanillin (1.4e^-6 and 2.2e^-6 M) hindered ileal smooth muscle contractility induced by both Ach and KCl. Vanillin (1.4e^-6 and 2.2e^-6 M) also caused a rightward shift of the Ach concentration response curve and brought about a decrease (21.6 and 38.3%, respectively) in the maximum response. It also produced a rightward shift in the KCl dose response curve but without affecting the maximum response. These results indicate that vanillin counteracts Ach and KCl induced smooth muscle contractility in rat ileum. The results also suggest that vanillin prevented Ach induced contractility via non competitive inhibition kinetics. The reduction in KCl induced contractility also indicates that vanillin, at least partially, conveyed its effect through acting on ileal smooth muscle calcium channels.

Key words: Vanillin, acetylcholine, KCl, rat Ileum, smooth muscle contraction.