Methoxydextran as an indicator of gastrointestinal transit in Japanese quail

The recovery of polyethylene glycol, a substance frequently used as an indicator of the dynamics in the liquid phase of intestinal chyme, is considerably influenced by the presence of trichloroacetic acid in certain applications. The suitability of (methoxy-14C)methoxydextrane as an intestinal indicator in the Japanese quail was tested in the study. After the administration of this indicator, the bird expires less than 1% of the substance in form of 14CO2. The recovery of labelled methoxydextrane is 98 +/- 7%. The distribution of the indicator within the segments of the gastrointestinal tract does not differ significantly from the distribution of (14C)polyethylene glycol 4000, measured in the absence of trichloroacetic acid. The transit of the labelled methoxydextrane into the jejunum did not reduce the radio-chemical purity of the isotope, as compared with its original purity before administration. A slight decrease was only recorded during the measurement of the cumulative excretion of the indicator for 72 hours, but this decrease has no influence upon the suitability of methoxydextrane as an intestinal indicator. (Methoxy-14C)methoxydextrane does not interact with trichloroacetic acid, whereas when polyethylene glycol is used as an indicator, the substance precipitates from the liquid phase just at the concentration commonly used for the removal of protein from biological samples.