Frog gastric mucosae bathed in chloride-free solutions

Abstract

The concept that the Cl^– and H⁺ mechanisms are electrogenic was tested with Cl^–-free preparations. With an in vitro chamber method it was found that in the resting mucosa bathed in sulfate the potential difference (p.d.) was about zero, and that histamine produced a negative p.d. (nutrient negative), a decrease in the electrical resistance, and H⁺ secretion. H⁺ secretion occurred in the absence of short-circuiting, but short-circuiting increased it. The H⁺ rate was only a fraction of that in Cl^– preparations. Clamping voltage in sulfate preparations at successively higher levels (nutrient positive) increased the H⁺ rate but not to the level in Cl^– solutions. In sulfate preparations thiocyanate on secretory side (10 mm) resulted in a decrease in H⁺ rate, an increase of p.d. (from –17 to +1), and a decrease in resistance. Changing either the secretory thiocyanate concentration over the range of from 10 to 108 mm or the Cl^– concentration from 0 to 108 mm produced relatively small changes in p.d., but marked changes in resistance. Findings explained on basis of electrogenic theory by postulation of a limited cytoplasmic biochemical coupling between Cl^– and H⁺ mechanisms.