A note on perfusion with labelled compounds to determine intestinal absorption

Abstract An in vivo perfusion technique has been adapted for the measurement of intestinal absorption of labelled compounds. Salicylic acid, labelled with 14C, in solution with or without phenylephrine or caffeine, was perfused through the ligated and cannulated small intestine in situ of the rat. Absorption was estimated from the difference in count of the solutions entering the gut and the outflow which was sampled at 10 min intervals. Some 40–45% of the acid was found to be absorbed at each of three consecutive 10 min samplings. This was lower than, but consistent with, reported results derived by chemical assay. In the presence of the other two drugs the absorption of salicylic acid increased to 70%.