title: [Regional differences in viscosity, elasticity and wall buffering function in systemic arteries: pulse wave analysis of the arterial pressure-diameter relationship].
abstract: OBJECTIVE
  Regional variations in the incidence of vascular diseases have been related to regional differences in arterial viscoelasticity. The aim of this study was to characterize the differences in the elastic and viscous modulus and in wall buffering function between central and peripheral systemic arteries, through a time-series analysis of the pressure-diameter relationship.
  
  
  METHODS
  Pressure and diameter were measured in seven arterial segments (carotid, brachiocephalic trunk, ascending aorta, proximal, middle and distal descending thoracic aorta, and femoral artery) from six sheep. Each segment was mounted on an in vitro mock circulatory system and perfused with Tyrode solution, with a pulse frequency of 1.8 Hz and systemic pressure levels. We used the Kelvin-Voigt model to calculate the pressure-diameter elastic (Epd, mmHg/mm) and viscous (Vpd, mmHg.s/mm) modulus, and to quantify the local wall buffering function (Vpd/Epd). We also calculated the incremental Young's and pressure-strain elastic modulus and pulse wave velocity for each segment.
  
  
  RESULTS
  The elastic and viscous modulus increased from proximal to distal segments. The wall buffering function did not differ significantly between arteries. The lower rigidity of the central arteries compared to the distal ones may indicate that the systolic arterial compliance function is concentrated in the central arterial segments. On the other hand, the greater viscosity in the distal segments may indicate that viscous energy loss is concentrated in these segments.
  
  
  CONCLUSIONS
  Arterial elasticity and viscosity can be interpreted as properties that are dependent on the region of the vessel, whereas wall buffering function can be considered region-independent.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. dbia@fmed.edu.uy
authors.forename: Daniel
authors.initials: D
authors.lastname: Bia
authors.forename: Ismael
authors.initials: I
authors.lastname: Aguirre
authors.forename: Yanina
authors.initials: Y
authors.lastname: Zócalo
authors.forename: Lucía
authors.initials: L
authors.lastname: Devera
authors.forename: Edmundo
authors.initials: E
authors.lastname: Cabrera Fischer
authors.forename: Ricardo
authors.initials: R
authors.lastname: Armentano
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology*; D001696:Biomechanical Phenomena; D002320:Cardiovascular Physiological Phenomena; D004548:Elasticity; D011674:Pulse; D012756:Sheep; D014783:Viscosity