Effect of atropine sulfate on gastric emptying and gastrocecal transit time evaluated by using the [1-13C]acetic acid and lactose-[13C]ureide breath test in conscious rats

Abstract

Breath tests have been used to investigate many physiological functions. Recently, we have developed a breath test system by using a non-invasive technique in conscious rats. In this study, we investigated the effect of atropine sulfate on the gastric emptying and gastrocecal transit time using [1-13C]acetic acid and lactose-[13C]ureide, respectively. Gastric emptying was significantly delayed by atropine sulfate in a dose-dependent manner (0.03–0.3 mg kg−1), but the effects of 0.1 and 0.3 mg kg−1 were almost equal. Cmax and Tmax values were also significantly and dose-dependently decreased and delayed, respectively. However, AUC120 min values were not significantly different for the three doses of atropine sulfate. This suggests that although atropine sulfate slows the emptying of the gastric content, it is excreted eventually to the same content as the control. The gastrocecal transit time was significantly delayed by atropine sulfate at a dose of 1 mg kg−1, but not at a dose of 0.1 mg kg−1. These findings demonstrate that the breath tests can evaluate the effect of atropine sulfate on the gastric emptying and gastrocecal transit time. The effective dose of atropine sulfate may be different for gastric emptying and gastrocecal transit time.