Simple and Noninvasive Breath Test Using 13C-Acetic Acid to Evaluate Gastric Emptying in Conscious Rats and Its Validation by Metoclopramide

Abstract

Abstract. The 13 C-breath test has been used to clinically evaluate gastric emptying. However, this method has not been sufficiently validated in experimental animals. The present study aimed to establish a simple and noninvasive 13 C-breath-test system in Sprague-Dawley male rats. After fasting, rats were orally administered Racol containing 13 C-acetic acid and housed in a desiccator. The expired air in the chamber was collected in a breath-sampling bag using a tube and aspiration pump. The level of 13 CO 2 in the expired air was measured using an infrared spectrometer at appropriate intervals for 120 min. During this period, the rate of 13 CO 2 excretion increased, peaked, and decreased thereafter. The maximum concentration (C max ) and area under the curve (AUC 120 min ) of 13 CO 2 excretion increased in volume-and dose-dependent manners. The time taken to reach the maximum concentration (T max ) of 13 CO 2 excretion increased as the volume increased, but was not affected by the dose of 13 C-labeled acetic acid. Metoclopramide dosedependently increased the C max and shortened T max of 13 CO 2 excretion compared with those of the control rats, whereas the AUC 120 min was not affected. These results confirm that this simple method can successfully evaluate gastric emptying. Moreover, this system is suitable for investigating additional physiological functions using other labeled compounds.

Rikkunshito, a Kampo Medicine, Ameliorates Post-operative Ileus by Anti-inflammatory Action

“…Whole-mount muscular (5 cm from ileocecal valve of the distal ileal region) samples were prepared as reported previously (15,17,18). Mucosa-free muscular whole mounts were fixed in 4% paraformaldehyde in PBS for 30 min at 4°C.…”

Usefulness of Breath Test for Evaluating Pancreatic Exocrine Function Using N-Benzoyl-L-tyrosyl-1-13C-L-alanine Sodium in Non-invasive and Conscious Rats

“…Therefore, we used our recently developed breath test system using conscious rats. 7) In the present study, exhaled C-L-alanine sodium is digested by the protease secreted from the pancreas, and that the monitoring of the expired 13 CO 2 air from this reflects the pancreatic exocrine function.…”

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.…”

“…C max and AUC 90 min reflect the absorption of labeled materials as reported previously. 8,9) In present study, C max and AUC 90 min were used to evaluate the peak and the amount, respectively, of 13 CO 2 extraction during 90 min. For evaluation of the gastroprokinetic agents, we studied the gastric half emptying (T 1/2 ) as the time when half of the AUC 90 min had been obtained.…”

“…Uchida et al modified the 13 C-breath test using rats and established a simple system using a desiccator and pump along with an infrared red spectrometer. 8) This method is a simple and non-invasive method for measurement of gastric emptying without causing rats stress. With this method, 13 C-acetic acid was found to be more sensitive for monitoring gastric emptying than 13 Coctanoic acid.…”