Response of active transport of ions and spontaneous water flux to osmotic gradients in gastric mucosa

The effects of symmetric changes of the mucosal and serosal bathing solution on cell water content, net ion flux, and net water movement were studied in the isolated frog gastric mucosa. Similar to transmucosal concentration gradients that induce water movement and changes in cell water content, symmetric osmolality changes of the bathing solutions also produce changes in these functional parameters. Thus, increments from 165 to 286 mosmol/kg water in the osmolality of both solutions reduce cell water content from 2.37 plus or minus 0.12 to 1.30 plus or minus 0.20 ml/g wt, the net ion flux (acid secretion plus short-circuit current) from 4.83 plus or minus 0.36 to 3.44 plus or minus 0.26 mueq/cm2 per h, and the net water flux from 10.6 plus or minus 1.1 to 2.4 plus or minus 1.2 mul/cm2 per h. These osmotically induced flux changes of water and ions must be considered when osmotic gradients are being used to generate and to evaluate water movement across the gastric mucosa.