RELEVANCE OF BLOOD-FLOW FOR THE ABSORPTION OF DRUGS IN THE VASCULARLY PERFUSED, ISOLATED INTESTINE OF THE RAT

1. The absorption of antipyrine, salicylic acid, and urea was measured in vascularly perfused segments of rat intestine. The results were compared with absorption in segments of intestine which were prepared in an identical manner, but not perfused with blood. 2. Compared to in situ results obtained earlier, the absorption of antipyrine and salicylic acid increased 3-fold; the absorption of urea, 2-fold. The absorption of the drugs in the unperfused segments was reduced 60%; however, the absorption of urea remained unchanged. Blood flow apparently limits drug absorption, but not urea absorption. 3. A certain amount of the drugs permeated into the serosal bath in the blood-perfused segments of intestine: approximately 20% of the antipyrine and urea, but only 2% of the salicylic acid. This accounts for the difference between the disappearance rate and the venous appearance rate. 4. Histological examination revealed no morphological alterations in the blood-perfused segments when compared with control specimens. The water and glucose absorption rates were within the range obtained in earlier in vivo investigations. 5. The glucose consumption of the tissue was increased in the non-vascularly perfused intestine; apparently the oxygen supply was insufficient. The histological alterations may be the result of insufficient oxygen supply or water storage within the tissue. © 1979 Springer-Verlag.