Acid-base changes across the wall of hamster and rat intestine

Abstract

1. 1. When small sacs of hamster small intestine were incubated in bicarbonate-saline gassed with 5% CO 2 and 95% O 2, the bicarbonate concentration and pH rose on the mucosal side while the reverse affect was noted on the serosal side. This concentration gradient of bicarbonate ions was completely inhibited anaerobically. 2. 2. In the lowest segment of the ileum a solution containing high concentrations of sodium bicarbonate was secreted from serosal to mucosal side. There was no appreciable movement of chloride ion across the wall under these conditions. 3. 3. The concentration of CO 2 was found significantly higher on the serosal than mucosal side. This evidence has been used to support the hypothesis involving an exchange of hydrogen ion for sodium ion across the serosal surface of the mucosal cell. 4. 4. Sacs of rat jejunum showed a fall in bicarbonate concentration on the mucosal side and a rise on tahe serosal side; sacs taken from athe taken from the lower region secreted a small amount of bicarbonate from serosal to mucosal sides. 5. 5. When bicarbonate-saline was placed in a washed loop of jejunum of an anesthetized rat the total CO 2 and pH fell; a similar solution in a loop of ileum of the same animal showed a rise in total CO 2 and pH.