H. Nanjo et al., AUTOREGULATION OF PORTAL CIRCULATION - A CORRELATIVE STUDY OF CIRCULATION AND VASCULAR MORPHOLOGY, Pathology international, 47(9), 1997, pp. 585-591
To investigate the mechanism of portal circulation and the genesis of
portal hypertension, an in vivo model was made to increase portal veno
us flow (PVF) by forming a bypass shunt between the femoral artery to
the splenic venous branch in pigs and dogs via a regulatable pump. Usi
ng this model, an autoregulatory hemodynamics of the portal circulatio
n and corresponding morphological changes of the intrahepatic vascular
system were determined, Immediately after blood flow increase (100 mL
/min) to the portal vein, PVF increased to the baseline level plus byp
ass shunt flow, But, PVF returned to the baseline level within 1 h for
both animals, Portal venous resistance (PVR) at 1 h was significantly
higher than the baseline level (P<0.05). By histometric analysis of t
he cross-sectional area of the portal and hepatic venous branches (CSA
-PV, CSA-HV) using the biopsized liver, CSA-HV at 1 h was 27.6% of the
CSA-HV of the baseline level in dog, which showed narrowing and contr
active changes of the hepatic venous branches, and CSA-PV at 1 h was 3
6.4% of the CSA-PV of the baseline level in pig, which showed narrowin
g and contractive changes of the portal venous branches, It is suggest
ed that a tone of the intrahepatic vascular system has an important ro
le in the portal autoregulatory hemodynamics.