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

• Published in: Scandinavian journal of gastroenterology 2012-02, Vol.47 (2), p.148-154
• Main Authors: Inada, Makoto, Kunizaki, Jun-ichi, Tobita, Kazuki, Akamatsu, Suguru, Sato, Hitoshi
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; breath test; Breath Tests; C]carbonate; calcium; Calcium Carbonate - analysis; Carbon Dioxide - administration & dosage; Carbon Dioxide - metabolism; Carbon Isotopes; CO3; Enzyme Inhibitors - pharmacology; gastric acid; Gastric Acid - metabolism; Gastric Acidity Determination; Gastroenterology. Liver. Pancreas. Abdomen; Hydrogen-Ion Concentration - drug effects; Medical sciences; Omeprazole - pharmacology; Pentagastrin - pharmacology; proton pump inhibitor; Rats; Rats, Sprague-Dawley; Rats, Wistar; Sodium Bicarbonate - administration & dosage
• ISSN: 0036-5521; 1502-7708
• DOI: 10.3109/00365521.2011.647066

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 saturated at >200 µmol/kg. The direct correlation between the breath-Cmax and the total amount of gastric acid in rats with or without OMPs or PG (r = 0.994) demonstrated that the change in breath response is an accurate or sensitive indicator of the total amount of gastric acid. 13CO2 gas generated in the rat stomach was likely to diffuse across the stomach wall as 13CO2 gas directly into the blood plasma. Conclusions. The present study showed that Ca13CO3 breath test is a good tool to accurately predict the total amount of gastric acid.