THE ABSORPTION OF PHENFORMIN AND ITS EFFECTS ON GLUCOSE AND WATER ABSORPTION IN ISOLATED PERFUSED RAT SMALL INTESTINE

The effects of phenformin on glucose and water absorption from isolated perfused rat small intestine were studied. Luminal phenformin inhibited glucose and water absorption progressively as its concentration was increased from 0·1-1·0 mg.ml -1 . At 0·5 mg phenformin ml -1 , inhibition increased with time of exposure to phenformin up to 15 min and thereafter remained constant. Arterial infusion of phenformin (1·0 mg.ml -1 ) produced less inhibition of glucose and water absorption. The site of phenformin's action appeared to be intracellular. Phenformin absorption from a luminal perfusate (0·5 mg.ml -1 ) was measured. Although it was rapidly absorbed (224 µg.cm intestine -1 .h -1 ) from the lumen, less than 2 µg.cm -1 .h -1 appeared at the serosal surface of the intestine. In subsequent phenformin-free perfusion, only 25% of the absorbed phenformin was recovered in the luminal and serosal effluents.