The sinusoidal barrier in rats with portacaval anastomosis: a morphometric study.

Shunting of portal blood in the rat leads to liver atrophy and to an increase in arterial blood flow with microcirculatory disturbances. The aim of this study was to investigate the effects of these disturbances on the liver sinusoidal barrier (endothelial and perisinusoidal cells) using morphometric techniques. Rats with portacaval anastomosis (PCA) and sham operated pair-fed controls were studied 3 months after the shunt. Sinusoidal volume density in PCA increased but not significantly and the volume density (Vv) of total endothelial (EC) and perisinusoidal cells (PSC) increased by 104.54% compared to sham operated pair-fed rats. The increase of EC Vv was not associated with an increase in surface density (Sv) suggesting a fall in the number of small fenestrations and an increase in cell thickness. This interpretation supports the morphological observations. The increase of PSC Vv was mainly related to the increase in their subendothelial processes Vv and not to that of the cell body Vv. Lipids Vv and RER Sv expressed per sinusoidal cells remained unchanged suggesting that the balance between the 2 hypothetical functions of the PSC, namely fibrogenesis and storage of vitamin A, was maintained. In conclusion, changes of EC and PSC after PCA result mainly in thickening of the sinusoidal barrier. This increase may impair exchanges between the sinusoidal lumen and Disse space and contribute to functional abnormalities.