Inhibition of intestinal sugar transport by phenformin

The effect of phenformin on the absorption of D-glucose and D-galactose by hamster and rat intestine, was studied. Phenformin did not affect D-glucose absorption by rat intestine, but it inhibited at 10(-3) to 10(-2) M the absorption of D-glucose and D-galactose by hamster intestine. The inhibition was higher when D-glucose was tested. Phenformin also inhibited active accumulation of these sugars by rings of hamster small intestine, in vitro; this effect was greater when D-glucose was utilized. The drug inhibits the oxygen uptake in the tissue in the absence or in the presence of added substrate. Phenformin, as previously suggested, does not seem to act as a specific inhibitor on D-glucose transport, but most likely by its inhibitory effect on mitochondrial respiration.