A method for the contemporaneous determination of oxygen consumption and of other chemical parameters in the isolated intestine

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.

Energy-rich phosphates and transintestinal transport in rat intestine incubated in vitro at different temperatures

In the present work, the transported fluid and the tissue content of ATP, ADP and AMP has been evaluated in the jejunum rat intestine which was everted and incubated in vitro both at 28 degrees C and at 38 degrees C for 1 h. The energy-rich phosphates have been measured in the tissue at the beginning and at the end of the experiment as well as in vivo. These determinations have been made in the total intestine and in the scraped mucosa. ATP and ADP content are higher in vivo and lower but constant at 28 degrees C in vitro; on the contrary, at 38 degrees C in vitro, the initial and final content of these adenilic nucleotides are both lower than at 28 degrees C. Under all these conditions the AMP content does not vary appreciably. Wet weight to dry weight ratios ahve been reported for mucosal and submucosal tissues in unincubated and incubated intestines. In some experiments, fluid transport (measured as an actual serosal volume increase) was determined every 20 min during a 1-h incubation. At 28 degrees C, fluid transport is constant throughout the time of the experiment, but at 38 degrees C, there is a progressive decrease of the transported fluid. Fluid transport and ATP content of the intestine seem to be directly related. The transport activity which is lower at 38 degrees C than at 28 degrees C, seems to be due to a low availability of energy-rich phosphates.