Transport of potassium by the gastric mucosa of the frog

¹ Department of Medicine, University of California School of Medicine, San Francisco, California

The transport of potassium across the isolated frog gastric mucosa was studied by the chamber method. The net flux of potassium from the nutrient to the secretory phase (J_ns^K) did not follow the predictions of simple passive diffusion when the mucosa was incubated with equivalent concentrations of K⁺ in the secretory and nutrient phases. Furthermore, a net gain in secretory potassium occurs against the electrochemical potential gradient if the mucosa is first incubated with nutrient solutions containing 4 mEq/1. of K⁺. Neither the loss of K⁺ from mucosal cells nor solvent drag appears to account for the positive values of J_ns^K under these circumstances. These data indicate, therefore, that there is a small but significant component of active potassium transport in this preparation.