title: Fluid mechanical consequences of pendular activity, segmentation and pyloric outflow in the proximal duodenum of the rat and the guinea pig.
abstract: We conducted numerical experiments to study the influence of non-propagating longitudinal and circular contractions, i.e. pendular activity and segmentation, respectively, on flow and mixing in the proximal duodenum. A lattice-Boltzmann numerical method was developed to simulate the fluid mechanical consequences for each of 22 randomly selected sequences of high-definition video of real longitudinal and radial contractile activity in the isolated proximal duodenum of the rat and guinea pig. During pendular activity in the rat duodenum, the flow was characterized by regions of high shear rate. Mixing was so governed by shearing deformation of the fluid that increased the interface between adjacent domains and accelerated their inter-diffusion (for diffusion coefficients approx. less than 10(-8) m&sup2; s(-1)). When pendular activity was associated with a slow gastric outflow characteristic of post-prandial period, the dispersion was also improved, especially near the walls. Mixing was not promoted by isolated segmentative contractions in the guinea pig duodenum and not notably influenced by pylorus outflow. We concluded that pendular activity generates mixing of viscous fluids 'in situ' and accelerates the diffusive mass transfer, whereas segmentation may be more important in mixing particulate suspensions with high solid volume ratios.
authors.affiliation: UMR 782 Génie et Microbiologie des Procédés Alimentaires, INRA, AgroParisTech, CBAI 78850 Thiverval Grignon, France. c.deloubens@grignon.inra.fr
authors.forename: Clément
authors.initials: C
authors.lastname: de Loubens
authors.forename: Roger G
authors.initials: RG
authors.lastname: Lentle
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Love
authors.forename: Corrin
authors.initials: C
authors.lastname: Hulls
authors.forename: Patrick W M
authors.initials: PW
authors.lastname: Janssen
mesh_terms: D000818:Animals; D004386:Duodenum / Q000502:physiology*; D005769:Gastrointestinal Motility; D006168:Guinea Pigs; D008954:Models, Biological; D019518:Postprandial Period; D051381:Rats
references.citation: J Physiol. 1955 Mar 28;127(3):553-63
references.pmid: 14368548
references.citation: Neurogastroenterol Motil. 2005 Jun;17 Suppl 1:22-30
references.pmid: 15836452
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Nov;78(5 Pt 2):056706
references.pmid: 19113236
references.citation: Am J Physiol. 1975 Jun;228(6):1887-92
references.pmid: 1155619
references.citation: Am J Physiol. 1994 Apr;266(4 Pt 1):G525-43
references.pmid: 8178991
references.citation: Am J Physiol Gastrointest Liver Physiol. 2000 Apr;278(4):G604-16
references.pmid: 10762615
references.citation: World J Gastroenterol. 2007 Mar 7;13(9):1365-71
references.pmid: 17457967
references.citation: Physiol Behav. 1973 Nov;11(5):687-704
references.pmid: 4748064
references.citation: J Comp Physiol B. 2006 Jun;176(5):469-75
references.pmid: 16482429
references.citation: Am Nat. 2000 Apr;155(4):544-555
references.pmid: 10753080
references.citation: Dig Dis Sci. 2010 Dec;55(12):3349-60
references.pmid: 20198425
references.citation: Am J Physiol Gastrointest Liver Physiol. 2003 Nov;285(5):G907-18
references.pmid: 14561588
references.citation: J Nutr. 1995 Sep;125(9):2348-55
references.pmid: 7666252
references.citation: Neurogastroenterol Motil. 2008 Dec;20(12):1317-27
references.pmid: 19019034
references.citation: J Physiol. 2004 Apr 15;556(Pt 2):557-69
references.pmid: 14754993
references.citation: Philos Trans A Math Phys Eng Sci. 2010 Jun 28;368(1921):2863-80
references.pmid: 20478911
references.citation: J Physiol. 2007 Aug 1;582(Pt 3):1239-48
references.pmid: 17495038
references.citation: J Med Res. 1902 Jan;7(1):72-5
references.pmid: 19971454
references.citation: Neurogastroenterol Motil. 2012 Jul;24(7):686-95, e298
references.pmid: 22540972
references.citation: J Theor Biol. 1998 Mar 7;191(1):63-78
references.pmid: 9593657
references.citation: Proc Biol Sci. 2004 Dec 22;271(1557):2587-94
references.pmid: 15615685
references.citation: J Comp Physiol B. 2005 Jul;175(5):337-47
references.pmid: 15928916
references.citation: Am Nat. 2000 Apr;155(4):527-543
references.pmid: 10753079
references.citation: J Comp Physiol B. 2007 Jul;177(5):543-56
references.pmid: 17342493
references.citation: Philos Trans A Math Phys Eng Sci. 2020 Sep 4;378(2179):20200168
references.pmid: 32762434
references.citation: J Physiol. 1972 Dec;227(2):611-25
references.pmid: 4647272
references.citation: Biochim Biophys Acta. 1977 Jul 20;488(1):25-35
references.pmid: 889858
references.citation: Am J Physiol. 1982 Dec;243(6):G541-50
references.pmid: 7149035
references.citation: Am J Physiol Gastrointest Liver Physiol. 2011 Apr;300(4):G577-85
references.pmid: 21193528