title: Computer three-dimensional reconstruction of the sinoatrial node.
abstract: BACKGROUND
  There is an effort to build an anatomically and biophysically detailed virtual heart, and, although there are models for the atria and ventricles, there is no model for the sinoatrial node (SAN). For the SAN to show pacemaking and drive atrial muscle, theoretically, there should be a gradient in electrical coupling from the center to the periphery of the SAN and an interdigitation of SAN and atrial cells at the periphery. Any model should include such features.
  
  
  RESULTS
  Staining of rabbit SAN preparations for histology, middle neurofilament, atrial natriuretic peptide, and connexin (Cx) 43 revealed multiple cell types within and around the SAN (SAN and atrial cells, fibroblasts, and adipocytes). In contrast to atrial cells, all SAN cells expressed middle neurofilament (but not atrial natriuretic peptide) mRNA and protein. However, 2 distinct SAN cell types were observed: cells in the center (leading pacemaker site) were small, were organized in a mesh, and did not express Cx43. In contrast, cells in the periphery (exit pathway from the SAN) were large, were arranged predominantly in parallel, often expressed Cx43, and were mixed with atrial cells. An approximately 2.5-million-element array model of the SAN and surrounding atrium, incorporating all cell types, was constructed.
  
  
  CONCLUSIONS
  For the first time, a 3D anatomically detailed mathematical model of the SAN has been constructed, and this shows the presence of a specialized interface between the SAN and atrial muscle.
authors.affiliation: University of Leeds, Leeds LS2 9JT, UK. bmshd@leeds.ac.uk
authors.forename: H
authors.initials: H
authors.lastname: Dobrzynski
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Tellez
authors.forename: I D
authors.initials: ID
authors.lastname: Greener
authors.forename: V P
authors.initials: VP
authors.lastname: Nikolski
authors.forename: S E
authors.initials: SE
authors.lastname: Wright
authors.forename: S H
authors.initials: SH
authors.lastname: Parson
authors.forename: S A
authors.initials: SA
authors.lastname: Jones
authors.forename: M K
authors.initials: MK
authors.lastname: Lancaster
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Honjo
authors.forename: Y
authors.initials: Y
authors.lastname: Takagishi
authors.forename: I
authors.initials: I
authors.lastname: Kodama
authors.forename: I R
authors.initials: IR
authors.lastname: Efimov
authors.forename: R
authors.initials: R
authors.lastname: Billeter
authors.forename: M R
authors.initials: MR
authors.lastname: Boyett
mesh_terms: D000818:Animals; D003198:Computer Simulation; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D008962:Models, Theoretical; D009206:Myocardium; D016900:Neurofilament Proteins / Q000032:analysis / Q000235:genetics; D011817:Rabbits; D012849:Sinoatrial Node / Q000033:anatomy & histology* / Q000166:cytology*
chemical_list: D016900:Neurofilament Proteins