13C-Acetic Acid Is More Sensitive Than 13C-Octanoic Acid for Evaluating Gastric Emptying of Liquid Enteral Nutrient Formula by Breath Test in Conscious Rats

Abstract

For evaluating gastric motility many methods have been reported, such as the gastrotonometry by the infused catheter method or microtransducer method, the radioactive isotope method and the acetaminophen method. 1)In 1993, Ghoos and colleagues 2) developed 13 C-breath test for monitoring gastric emptying as a nonradioactive alternative method. By using this method, gastric emptying time can be indirectly measured by monitoring the 13 CO 2 concentration in the expired air after a 13 C-labeled substance, such as acetic acid or octanoic acid, was ingested and absorbed from the duodenum.1-3) Thereafter breath tests using 13 C-labeled compounds have been used in laboratory animals for evaluating physiological function, such as gastric empying 4,5) or liver function. 6) Recently, the present authors reported simple and noninvasive breath test system for monitoring gastric emptying by using 13 C-labeled acetic acid in conscious rats. 7)13 C-Labeled acetic acid or 13 C-labeled octanoic acid has been used generally in clinic for evaluating gastric emptying. 13C-Labeled acetic acid has been used in the form of liquid test meal, such as coffee or juice. On the contrary, 13 C-labeled octanoic acid has been used in the form of solid test meal, such as egg yolk or steak. This reason is that octanoic acid is slightly soluble in water and acetic acid in lipid. Therefore, there are few reports comparing 13 C-labeled acetic acid and 13 C-labeled octanoic acid in the same test meal. Racol is liquid enteral nutrient and used in Japan as a liquid test meal for evaluating gastric emptying in clinic. Although Racol is liquid form, it contains lipid at a concentration of 4.46 g/200 ml. Therefore, octanoic acid can be solved in lipid if added to Racol.Then, in the present study the expired air pattern from 13 Clabeled acetic acid was compared with that from 13 C-labeled octanoic acid in the same test meal of Racol by using the breath test system newly developed by the present authors. 7) MATERIALS AND METHODS AnimalsThe following animal studies were performed according to "Guiding Principles for the Care and Use of Laboratory Animals" approved by The Japanese Pharmacological Society.Male Sprague-Dawley rats (200-250 g) were purchased from SLC (Shizuoka, Japan), and fasted in meshed cages for 18 hr to prevent coprophagy before the each experiment, but free access to drinking water. Evaluation System of Gastric Emptying by Breath Test Schematic illustration of apparatus for monitoring13 CO 2 expired air from rats reported by the present authors 7) was shown in Fig. 1. In brief, this system is composed with animal chamber (desiccator; 2000 ml), pump (Masterflex L/S, Cole-Palmer Inst. Co., U.S.A.) and breath sampling bag (Ohtsuka Pharmaceutical Co. Ltd., Japan). Collected 13 CO 2 air was measured with UBiT IR-300 and UBiT-AS10 (Ohtsuka Electronics Co., Ltd., Japan).Rats were placed in the chamber just after the oral admin- C-Octanoic Acid for Evaluating Gastric Emptying of Liquid Enteral Nutrient Formula by Breath Test in Conscious RatsMas...

The 13C-Butyrate Breath Test: a New Non-Invasive Method for Assessing Colitis in a Murine Model

“…Therefore, we planned to use this model to test the efficacy of SASP. The decrease in 13 CO 2 in expired breath after rectal administration of 13 C-butyrate supports the view that 14 CO 2 production decreases after incubation with 14 C-butyrate in isolated colonocyte from DSSinduced murine colitis (17). These changes were statistically analyzed for correlations between other parameters frequently used to assess inflammation in murine colitis.…”

“…The mice were then held upside down while the anus was pinched with a clip (AS-1-40; Natsume Seisakusho Co., Ltd., Tokyo) to avoid reflux from the rectum to the anus. To collect the air in the chambers, we used the noninvasive breath test system as described previously (14,15). This system was comprised of four animal chambers, a pump, and breath sampling bags.…”

Update on diagnostic value of breath test in gastrointestinal and liver diseases

“…Principle: This test is established on the fact that time taken up by the transport of the tracer substance is considered the rate limiting state together with the ingested food from the stomach into the duodenum, while the remaining processes till the elimination of CO2 follows at a constant rate [50] . Protocol: Egg yolk is used as a test meal labeled with 13Coctanoic acid.…”

Validation of 13C-Acetic Acid Breath Test by Measuring Effects of Loperamide, Morphine, Mosapride, and Itopride on Gastric Emptying in Mice

“…The apparatus for monitoring 13 CO 2 levels in air expired by mice was modified from the rat model described by Uchida et al 8,9) In brief, this system is composed of a bottle top filter (Nalgene, 500 ml, 75 mm diameter membrane, 35 mm neck) connected to a 50 ml glass bottle, pump (Masterflex 7524-50, Cole-Palmer Instruments Co., Vernon Hills, U.S.A.), and a breath sampling bag (Ohtsuka Pharmaceutical Co., Ltd., Tokyo, Japan). The bottle top filter was used as the animal chamber; the filter was removed, and three holes (1 mm in diameter) were made in the top of the chamber as air inlet holes.…”

“…With this method, 13 C-acetic acid was found to be more sensitive for monitoring gastric emptying than 13 Coctanoic acid. 9) This test can successfully evaluate gastric emptying and can be used to study gastric prokinetics in the models of gastric motility disorders. The 13 C-breath test will be useful as a new tool to investigate the effects of drugs on gastric motility for further development.…”