Transport of Calcium and Inorganic Phosphate across the Intestinal Wall of the Rat

　The mode of transport of calcium and inorganic phosphate was investigated in the everted sac of rat intestine．

1）The absorptive capacity for both calcium and phosphate is greatest at the jejunum and decreases at lower parts of intestine．

2）In jejunum and ileum, calcium is transported actively from the mucosal side to the serosal side, but its relative magnitude in the total influx is not large．

3）The phosphate transport is apparenly explained in terms of electrochemical gradient, but the mechanism of transport is not simple free diffusion, because by the change of the potential difference the flux ratio becomes different from that calculated under the assumption of simple free diffusion．

4）At low temperature the net water flux increases but the influx of calcium and phosphate decreases．

5）The solvent drag force has a minor role for the transport of these substances under normal conditions．