title: Validation of octanoate breath test for measuring gastric emptying in rats.
abstract: OBJECTIVE
  Lack of simple and repeatable tests hampers gastric emptying studies in rats. The aim of this study was to adapt the (14)C-octanoate solid gastric emptying breath test for application in rats, and to validate it against radioscintigraphic method.
  
  
  METHODS
  After ingestion of a meal containing 3 mCi (99m)Tc and 2 µCi (14)C-octanoate, 23 male Wistar rats were placed on a gamma camera in a airflow container. Scintigraphic images were taken at regular intervals. The amount of (14)CO2 in a regularly replaced hyamine hydroxide solution, capturing CO2 in the outflow air, was counted using liquid scintillation spectrometry. (99m)Tc gastric retention curves and (14)CO2-excretion curves were fitted to their respective data. Three rats underwent the same procedures after administration of atropine.
  
  
  RESULTS
  Overall Tr10% (time at which 10% of the original amount of (99m)Tc remained in the stomach) was 355 ± 64 minutes; Te90% (time at which 90% of total amount of (14)CO2 was excreted) was 325 ± 106 minutes. Their correlation coefficient was 0.71, R-square 0.50 and P < 0.005. Tr1/2 (50% of original amount of (99m)Tc remained) was 124 ± 28 minutes; Te1/2 (50% of total amount of (14)CO2 excreted) 114 ± 32 minutes. Their correlation coefficient was 0.83 with R-square of 0.69 and P < 0.00005. In 12 immobilized animals correlation was even better: correlation coefficient 0.84; R-square 0.71 and P < 0.001 (Tr10% was 388 ± 117 minutes; Te90% 532 ± 219 minutes; Tr1/2 of 165 ± 54 minutes; Te1/2 of 175 ± 67 minutes). Atropine significantly lengthened all emptying times: 904 ± 307 and 1461 ± 684 minutes for Tr10% and Te90%, respectively; and 432 ± 117 minutes for Tr1/2 and 473 ± 190 minutes for Te1/2.
  
  
  CONCLUSIONS
  We adapted and validated the (14)C-octanoate gastric emptying breath test for application in rats.
authors.affiliation: Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Demedts
authors.forename: Christophe
authors.initials: C
authors.lastname: Vanormelingen
authors.forename: Hubert
authors.initials: H
authors.lastname: Van Billoen
authors.forename: Tim
authors.initials: T
authors.lastname: Vanuytsel
authors.forename: Ricard
authors.initials: R
authors.lastname: Farré
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Masaoka
authors.forename: Alfons
authors.initials: A
authors.lastname: Verbruggen
authors.forename: Kristien
authors.initials: K
authors.lastname: Verbeke
authors.forename: Pieter
authors.initials: P
authors.lastname: Vanden Berghe
authors.forename: Jan
authors.initials: J
authors.lastname: Tack
keywords: 14C-octanoate; Breath tests; Gastric emptying; Rats