Abstract:

 Objective   To study the influence of midazolam, propofol, etomidate and ketamine on the contraction of colonic longitudinal muscle in rats. Methods   Longitudinal muscle strips of colon were dissected from male Wistar rats and randomly divided into control group, TTX-free group and TTX group. Some strips were exposed to Kreb′s solution with 1‰ DMSO (control group). Some other strips were incubated within Kreb′s solution containing midazolam, propofol, etomidate and ketamine with (TTX group) or without (TTX-free group) tetrodotoxin pre-treatment. Isometric contraction of longitudinal smooth muscle strips was measured and recorded. Result   1‰ DMSO exerted no effect on the tension of colonic strips in control group. Midazolam, propofol,  etomidate and ketamine at accumulating concentration of 1×10-5 mol/L, 1×10-5 mol/L, 1×10-6 mol/L and 3×10-6 mol/L decreased the tension of colonic strips in a concentration-dependent manner (P＜0.05～0.01) in TTX-free group. Pre-treated with TTX, midazolam, propofoland etomidate all produced greater reduction of strip tension in TTX group than that in TTX-free group, while ketamine enhanced the strip tension in the presence of TTX. Conclusion   Midazolam, propofol, etomidate and ketamine exhibit inhibitory effects on the spontaneous contractile activities of isolated colonic strips in rats. The contraction of smooth muscle cells and activity of enteric nervous system might be involved in this effect.

Key words: Anesthetic agents, intravenous; Colon; Motility; Rats, Wistar