Assessment of gastric emptying in the mouse using the [C-13]-octanoic acidbreath test

1. Gastric emptying studies in small laboratory animals are hampered by the deficiency of a technique that is non-invasive and repeatable, The aim of the present study was to adapt the non-invasive [C-13]-octanoic acid breath test, which has been validated in humans, to assess both liquid and solid gastric emptying in the mouse. 2. Gastric emptying rates were investigated for a liquid meal (Intralipid(R ); Kabi Pharmacia AB, Stockholm, Sweden; n = 7) and two solid meals (egg yo lk and mouse chow; n = 7) incorporating [C-13]-octanoic acid, All meals wer e analysed for natural enrichment of [C-13]. Mathematical analysis of the ( CO2)-C-13 excretion rate allowed the determination of gastric emptying para meters. 3. Gastric emptying of Intralipid(R) was more rapid than egg yolk (P < 0.00 01). Gastric emptying of mouse chow could not be assessed due to intragastr ic separation of [C-13]-octanoic acid and natural [C-13] enrichment of the pellet. 4. The [C-13]-octanoic acid breath test can reproducibly assess both liquid and solid gastric emptying non-invasively in the mouse. This method can no w be used to assess gastric emptying in drug studies and disease studies fo r which there are established mouse models.