Application of Three Kinds of Dyes in Gastrointestinal Propulsion in Mice

In order to select the best tracer dye for gastric emptying and intestinal propulsion experiment,three kinds of dyes including of dextran blue 2000,direct blue 53 and ink were selected.The absorbance values of the series of concentration of dyes were tested in a range of wavelength by micro double dilution method.Moreover,the maximum absorption wavelength and measurable concentration range of three dyes were determined.According to measurable range of three kinds of dyes,the optimal gavage doses were obtained in mice.The gastric residual rates,small intestinal propulsion rates and residual rates in four parts of equal small intestine were tested.The results showed that the maximum absorption wavelengths of dextran blue 2000,direct blue 53 and ink were 630,630 and 405 nm,respectively.Their measurable concentration ranges were 0.16 to 5.00 mg/mL (R²=0.9863),0.78 to 6.25 μg/mL (R²=0.9984) and 0.02% to 0.16% (R²=0.9979).The difference of gastric emptying rates among the three dyes was not significant (P > 0.05),and intestinal propulsion rate of direct blue was significantly higher than those of the other two dyes (P < 0.05).Total residual rates of dextran blue 2000,ink and direct blue were 93.6%±4.5%,71.5%±8.5% and 18.7%±2.8%,respectively.The results suggested that ink was the best tracer dye if only the intestinal propulsion rate in vivo needed to be determined,while dextran blue 2000 is appropriate if a precise determination of the gastric and intestinal emptying needed to be done.