Effect of inhibitors on the intestinal active transport of glucose in tortoise

Glucose intestine active transport in tortoise Testudo hermanni robertmertensi Wermuth has been studied in vitro in the presence of known sugar active transport inhibiting substances. The final Serosal/Mucosal gradient is practically the same in aerobic and anaerobic conditions. A 10(-4) M concentration of DNP inhibits active transport of glucose and increases O2 uptake; a 10(-3) M concentration reinforces transport inhibition and lowers O2 uptake to normal values. Nullification of glucose active transport was not achieved by any of the DNP essayed concentrations. NaF greatly inhibits both glucose active transport and O2 uptake, whereas phlorizin inhibits transport and does not affect respiration. Tortoise intestine is able to obtain the required energy for its glucose active transport through both aerobic and anaerobic metabolism. Besides its oxidative phosphorylation uncoupling action, DNP also appears to affect glycolysis. Glycolysis inhibition and intestinal epithelial alteration may be responsible for the strong inhibition caused by NaF. Phlorizin seems to inhibit sugar transport by competence on the sugar carrier, at membrane level, without disturbing cellular metabolism.