Calcium [13C]carbonate breath test for quantitative measurement of total gastric acid in rats

Abstract Objective. A traditional measurement of gastric acid, involving nasogastric intubation of stomach and acid suction, has been suggested as a gold standard. However, this causes the patient discomfort and cost increase, and is ‘time-consuming’. Material and methods. A calcium [13C]carbonate (Ca13CO3) breath test was carried out in rats without or with concomitant drugs omeprazole (OMP) and pentagastrin (PG) known as an inhibitor and an inducer of acid, respectively. This test was aimed at evaluating a correlation between the breath response and the total amount of gastric acid. To search for an absorption pathway of 13CO2 gas produced by the reaction of Ca13CO3 with hydrochloric acid in the stomach of rats, we compared the breath responses after intra-gastric administration of 13CO2 gas and sodium [13C]bicarbonate (NaH13CO3). Results. A linear relationship of the breath parameter (breath-Cmax) with the dose of Ca13CO3 was obtained in the range of 4–200 µmol/kg. However, theses parameters were satur...