Oxygen consumption and active transport of ions by isolated frog gastric mucosa

Abstract

Isolated bullfrog gastric mucosae were suspended between two glass chambers and bathed with physiological salt solutions equilibrated with 5% CO₂ and 95% O₂. The transmucosal potential difference, short-circuit current and membrane conductance were measured. Oxygen consumption was measured polarographically and the rate of acid secretion was determined by the pH stat method. Values for the ratio of hydrogen ions secreted to the total oxygen molecules consumed were calculated for 84 experiments and yielded a mean ratio of 1.86 ± 0.51 (sd) with none of the values above 3.5. The ratio of chloride ions transported (calculated as short-circuit current of chloride ions plus hydrochloric acid) to total oxygen consumed for 84 experiments was found to be above 4.0 in 40% of the cases measured (mean 3.80 ± 0.68). A simple redox-pump hypothesis, with molecular oxygen as the electron acceptor, and with one ion moved for each electron transmitted is ruled out as the only operating mechanism to account for active chloride transport by frog gastric mucosa.