title: Mixing and pumping functions of the intestine of zebrafish larvae.
abstract: Due to its transparency, the intestine of zebrafish larvae has been widely used in studies of gastrointestinal diseases and the microbial flora of the gut. However, transport phenomena in the intestine of zebrafish larvae have not been fully clarified. In this study, therefore, transport caused by peristaltic motion in the intestine of zebrafish larvae was investigated by numerical simulation. An anatomically realistic three-dimensional geometric model of the intestine at various times after feeding was constructed based on the experimental data of Field et al. (2009). The flow of digested chyme was analyzed using the governing equations of fluid mechanics, together with peristaltic motion and long-term contraction of the intestinal wall. The results showed that retrograde peristaltic motion was the main contributor to the mixing function. The dispersion caused by peristalsis over 30min was in the order of 10-12m2/s, which is greater than the Brownian diffusion of a sphere of 0.4µm diameter. In contrast, anterograde peristaltic motion contributed mainly to the pumping function. The pressure decrease due to peristalsis was in the order of millipascals, which may reduce the activation and maintenance heat of intestinal muscle. These findings enhance our understanding of the mixing and pumping functions of the intestine of zebrafish larvae.
authors.affiliation: Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, 6-6-01 Aoba, Sendai 980-8579, Japan. Electronic address: yang@pfsl.mech.tohoku.ac.jp.
authors.forename: Jinyou
authors.initials: J
authors.lastname: Yang
authors.affiliation: Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aoba, Sendai 980-8578, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Shimogonya
authors.affiliation: Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, 6-6-01 Aoba, Sendai 980-8579, Japan; Department of Finemechanics, Graduate School of Engineering, Tohoku University, 6-6-01 Aoba, Sendai 980-8579, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D000465:Algorithms; D000818:Animals; D007422:Intestines / Q000502:physiology*; D007814:Larva / Q000502:physiology; D008954:Models, Biological; D009038:Motion; D010528:Peristalsis / Q000502:physiology*; D011312:Pressure; D013997:Time Factors; D015027:Zebrafish / Q000502:physiology*
keywords: Fluid mechanics; Numerical simulation; Peristaltic motion; Transport phenomena; Zebrafish intestine