抄録
The absorption and metabolism of p-aminobenzoic acid (PABA) was studied using the in vitro everted sac of rat intestine. PABA was metabolized to p-acetamidobenzoic acid (Ac-PABA) in the intestinal mucosa at the concentration of 5×10-5 M PABA. The Ac-PABA formed was released into mucosal and serosal fluid. The mucosal disappearance rate of PABA and the formation of Ac-PABA showed a dose dependency in the concentration range from 3×10-5 to 10-3 M. The mucosal disappearance rate of Ac-PABA was much slower than PABA. Major N-acetyltransferase activity was found in the mucosal 9000×g supernatant fraction. High activity was found in both small and large intestinal mucosa. The small intestinal N-acetyltransferase of rat readily catalyzed the acetylation of PABA, p-aminohippuric acid, p-aminosalicylic acid, but was considerably less active towards sulfonamides. The significance of intestine as the metabolic organ was suggested in relation to the first-pass effect.
