Method for Studying the Permeability of the Rat Intestinal Tract to Carbon Tetrachloride

Abstract

Previous inhalation studies with ¹⁴CC1₄ in rats and monkeys have shown significant amounts of unidentified ¹⁴C compound(s) to be excreted in the feces. The isolated gut sac was used to determine if CC1₄ could potentially be eliminated by intestinal exsorption, the direct transfer from blood to the intestinal lumen. Segments of duodenum, jejunum, ileum, and colon were removed, ligated at one end, and placed in a tissue bath filled with buffer containing CC1₄. Serosal and mucosal fluids were analyzed for CC1₄ by gas chromatography. Fick's law of diffusion was used to determine the permeability coefficient of CC1₄. The kinetic analysis is simplified when sink conditions prevail, i.e., the serosal concentration is constant and much greater than the mucosal concentration. There was significant loss of CC1₄ from the serosal buffer due to the need to oxygenate with 95% O₂ 5% CO₂, making accurate determination of permeability impossible. Saturation of the carbogen with CC1₄ resulted in a steady-state concentration in the serosal buffer. The permeability of CC1₄ was similar in all three segments of the small intestine. Permeability in the colon was slightly less than in the small intestine. This method allows for the study of the direct intestinal elimination of volatile solvents.

Key Words: :

• Intestinal exsorption
• Fecal elimination
• Isolated intestinal segment
• Carbon tetrachloride