Some Quantitative Studies on Phlorizin Inhibition of Glucose Transport in the Kidney

Abstract

The constant infusion of phlorizin in small amounts (0.6–100 µg/kg/min.) reduces maximal glucose transport rate (Tmg) by 20–70% in dogs. Thus phlorizin is a much more powerful inhibitor of glucose transport than hitherto supposed. From these experiments it is reasonable to conclude that effective phlorizin concentrations in the intact animal are in the same range as those shown to produce effects on sugar transport and oxidative metabolism in vitro. Complete inhibition of glucose transport during constant infusion of phlorizin was never produced even at rates of 100 µg/kg/min. Experiments on citrate metabolism in vitro and Tmg in vivo show that phlorizin does not act at a site sensitive to 2,4-dinitrophenol. The findings presented are discussed in the light of a cell membrane theory of phlorizin action.