title: In vivo ultrasound assessment of gastric emptying in newborn mice.
abstract: OBJECTIVE
  The aim of the present study was to develop an ultrasonographic approach to comparatively assess gastric emptying in newborn wild-type and guanosine triphosphate cyclohydrolase knockout hph-1 mice, because we previously reported gastroparesis early in life in this strain.
  
  
  METHODS
  Stomach transverse, anteroposterior, and longitudinal ultrasonographic measurements were obtained with a 40-MHz transducer in pups immediately after maternal separation and 4 hours later. A conventional equation was used and the predicted values validated by obtaining postmortem gastric content volume measurements. Wild-type and hph-1 mice gastric emptying rates were comparatively evaluated at 1 to 3 and 5 to 8 days of age, respectively.
  
  
  RESULTS
  The ultrasound equation closely predicted the newborn stomach content volumes with a correlation coefficient (R) of 0.93 and 0.81 (P < 0.01) for measurements obtained on full stomach and after 4 hours of fasting, respectively. In wild-type mice, gastric emptying was age dependent and associated with a greater residual volume at 1 to 3 days (65% ± 7%), as compared with 5- to 8-day-old pups (33% ± 4%; P  < 0.01), after fasting. In contrast, an equal duration of fasting resulted in a significantly greater residual gastric content volume in 5- to 8-day-old hph-1 mice (68%  ± 7%; P < 0.01), as compared with same-age wild-type mice.
  
  
  CONCLUSIONS
  Ultrasonography offers a sensitive and accurate estimate of gastric content volume in newborn mice. In wild-type newborn mice, gastric emptying rate is age dependent and significantly reduced in the immediate postnatal period. The newborn hph-1 mice have a significantly higher gastric residual volume, as compared with wild-type same-age animals.
authors.affiliation: *Physiology & Experimental Medicine Program, Department of Paediatrics †Department of Diagnostic Imaging, The Hospital for Sick Children and the University of Toronto, Toronto, ON, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Welsh
authors.forename: Jose
authors.initials: J
authors.lastname: Jarrin
authors.forename: Alan
authors.initials: A
authors.lastname: Daneman
authors.forename: Jaques
authors.initials: J
authors.lastname: Belik
mesh_terms: D000465:Algorithms; D000818:Animals; D000831:Animals, Newborn; D001708:Biopterins / Q000031:analogs & derivatives / Q000172:deficiency / Q000378:metabolism; D005240:Feasibility Studies; D005260:Female; D005746:Gastric Emptying; D005753:Gastric Mucosa / Q000000981:diagnostic imaging* / Q000254:growth & development / Q000378:metabolism / Q000473:pathology; D018589:Gastroparesis / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009929:Organ Size; D063150:Polycomb Repressive Complex 1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D013270:Stomach / Q000000981:diagnostic imaging* / Q000254:growth & development / Q000473:pathology; D014463:Ultrasonography
chemical_list: C103827:Phc1 protein, mouse; D001708:Biopterins; D063150:Polycomb Repressive Complex 1; C003402:sapropterin