Bidirectional Permeation of Water and Amino Acids in the Cecum of Germfree Rats

Abstract

The purpose of this work was to study transport across the cecal wall of germfree animals which has been found altered in previous experiments. Germfree (gf) and conventional control (conv) male Fisher (Ch.R., CD-F) rats, 8–10 months old, fed sterilized 5010C (water expt) or L-462 (amino acid expt) diets were used in urethane anesthesia (150 mg/100 g bodyweight). The labels employed were tritiated water, ¹⁴C UL glycine and serine in doses of 10 μC/rat. Absorption was studied by injection of the label into the intact cecal sack which was ligated at the emergence of the ileum and of the colon, and by the successive recovery from its contents. Efflux into the cecum was observed after injection into the saphenous vein. The duration of the experiment averaged 20 minutes. The corrected body weight was approx. 300 g in the 24 gf and 26 conv rats used to date in this series. The ceca of the gf rats were considerably enlarged (avg. 11% of the body weight); their contents were rather liquid (avg. 18% dry matter) and their osmolality was similar to that of blood plasma (in mOsm, mean, blood plasma 335 ± 10, gf cecal contents 326 ± 24). The results indicated that the efflux of tritiated water from blood into the cecum was increased in the gf group in comparison to conv controls.