Concentration and localization of calcium in frog gastric mucosa.

SCHWARTZ, MANUEL, HERBERT K. KASHIWA, AHREN JACOBSON, AND WARREN S. REHM. Concentration and locali<ation of calcium in frog gastric mucosa. Am. J. Physiol. 2 12(2) : 241246. I g67.-Removal of Ca $3from the solutions bathing the frog gastric mucosa results in an initial increase in resistance (first phase) and a decrease in the H+ secretory rate of about 4oy0. These effects are followed by a pronounced decrease in resistance (second phase) and a decrease in the H+ rate to zero. Restoration of Ca* to the nutrient solution reverses these effects. Chemical analysis of the frog gastric mucosa by atomic absorption spectrophotometry showed that at the peak of the first phase there was a 50% loss of tissue Ca* and no significant further loss by the time the H+ rate reached zero. Localization of Ca++ in the mucosal cells using glyoxal-bis (2-hydroxyanil) (GBHA) was found feasible. There was a marked reduction of the number of red GBHA-stainable Ca* granules in the tubular cells at the peak of the first phase. In the second phase, by the time the H+ rate reached zero the granules were absent from the tubular cells. Restoration of Ca* to the nutrient solution resulted in a distribution of red granules in the tubular cells corresponding to that of the controls. The evidence supports the conclusion that GBHA-stainable Ca* can readily leave and enter the tubular cells.