title: Constriction rate variation produced by partial ligation of the portal vein at pre-hepatic portal hypertension induced in rats.
abstract: BACKGROUND
  Partial portal vein ligation causes an increase in portal pressure that remains stable even after the appearance of collateral circulation, with functional adaptation to prolonged decrease in portal blood flow.
  
  
  OBJECTIVE
  To assess whether different constriction rates produced by partial ligation of the vein interfere with the results of this experimental model in rats.
  
  
  METHODS
  Three groups of five rats each were used; in group 1 (sham-operated), dissection and measurement of portal vein diameters were performed. Portal hypertension was induced by partial portal vein ligation, reducing its size to 0.9 mm in the remaining 10 animals, regardless of the initial diameter of the veins. Five animals with portal hypertension (group 2) underwent reoperation after 15 days and the rats in group 3 after 30 days. The calculation of the constriction rate was performed using a specific mathematical formula (1 - π r 2 / π R2) x 100% and the statistical analysis with the Student t test.
  
  
  RESULTS
  The initial diameter of the animal's portal vein was 2.06 mm, with an average constriction rate of the 55.88%; although the diameter of the veins and the constriction rate in group 2 were lower than in group 3 (2.06 mm - 55,25% and 2.08 mm - 56.51%, respectively), portal hypertension was induced in all rats and no significant macroscopic differences were found between the animals that were reoperated after 15 days and after 30 days respectively, being the shorter period considered enough for the evaluation. Comparing the initial diameter of the vein and the rate of constriction performed in groups 2 and 3, no statistic significance was found (p>0.05).
  
  
  CONCLUSIONS
  Pre-hepatic portal hypertension in rat can be induced by the reduction of the portal vein diameter to 0.9 mm, regardless the initial diameter of the vein and the vessel constriction rate.
authors: Universidade Nove de Julho, São Paulo, SP, Brasil.
authors: Daren Athiê Boy
authors: DA
authors: Rodrigues
authors: Universidade Nove de Julho, São Paulo, SP, Brasil.
authors: Aline Riquena
authors: AR
authors: da Silva
authors: Universidade Nove de Julho, São Paulo, SP, Brasil.
authors: Leonardo Carvalho
authors: LC
authors: Serigiolle
authors: Universidade Nove de Julho, São Paulo, SP, Brasil.
authors: Ramiro de Sousa
authors: Rde S
authors: Fidalgo
authors: Universidade Nove de Julho, São Paulo, SP, Brasil.
authors: Sergio San Gregorio
authors: SS
authors: Favero
authors: Universidade Nove de Julho, São Paulo, SP, Brasil.
authors: Pedro Luiz Squilacci
authors: PL
authors: Leme
mesh_terms: D000818:Animals; D003251:Constriction, Pathologic; D004195:Disease Models, Animal; D005260:Female; D006975:Hypertension, Portal; D008026:Ligation / Q000379:methods; D011169:Portal Vein / Q000601:surgery; D051381:Rats; D017208:Rats, Wistar
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