The utility of noninvasive 13C-acetate breath test using a new solid test meal to measure gastric emptying in mice

In clinical and experimental settings, the 13C breath test is performed to measure gastric emptying and has advantages of noninvasiveness and repeatability. We intended to apply the 13C breath test method to mice with an easy-to-handle solid test meal that is more physiological than liquid meals. Male ddY mice were trained to eat 13C-acetate-containing pellets as the solid test meal. Thirty minutes after administration of metoclopramide (0.3-3 mg/kg, p.o.) or atropine sulfate (0.3-3 mg/kg, i.p.), mice received the test meal and were placed in chambers. The 13CO2 levels in the expired air were measured and the maximum concentration (Cmax; ‰) and the time to reach the maximum concentration (Tmax; min) were determined. Metoclopramide significantly and dose-dependently increased Cmax and decreased Tmax. On the other hand, atropine sulfate significantly and dose-dependently decreased Cmax and increased Tmax. The 13C-acetate breath test using a solid test meal is sensitive enough to detect both enhanced and delayed gastric emptying of the reference drugs.