Lactate and bicarbonate transport in rat and hamster jejuna incubated in vitro

The transport of electrolytes into the serosal compartment of everted rat and hamster jejuna, incubated "in vitro" for 1 h, has been evaluated both at 38 degrees C and 28 degrees C. In order to determine the bicarbonate concentration in this compartment, pH and pCO2 were measured. It appears that, under both these experimental conditions, a relationship exists between lactate transport and pCO2 in the serosal side. A diffusion of undissociated lactic acid from the cellular into the serosal compartment is suggested. Oxygen consumption was approximately identical, at 28 degrees C, in both species. If the above assumption is correct, in the rat the anions which follow sodium during its active transport are mainly bicarbonate and chloride, while in the hamster jejunum, sodium is followed by chloride alone.