The portacaval and splenocaval shunt in the normal rat. A morphometric and functional reevaluation.

Consequences of a portacaval and a distal splenocaval shunt on the liver were examined in normal male rats with measurements of the fractional clearance of ICG, of aminopyrine demethylation and of the hepatic ultrastructure with morphometric techniques. Twenty days after a portacaval shunt liver weight/100 g body weight was 30% smaller than in sham-operated controls. The most pronounced reduction of 50% occurred with surface area of the RER, whereas hepatocyte volumes, SER-surface area, mitochondria and peroxisomes were reduced between 30 and 40% hepatogenic lysosomes and non-hepatocytes/100 g b.wt. remained unchanged. The loss of liver mass is therefore compatible with the hypothesis, that it is the consequence of a decrease in synthetic and an increase in catabolic processes. The rate of elimination of ICG from plasma was proportional to the liver weight (r = 0,79, n = 20) and 14C-exhalation derived from [14C]aminopyrine was correlated with the surface of the SER (r = 0.72, n = 20), confirming that the morphometrically observed changes are functionally relevant. The lack of morphological and functional sequelae following distal splenocaval shunt suggests that blood drained by the splenic vein is not essential for the integrity of the liver in rats.