Effect of portacaval shunt on biliary cholesterol and bile salt secretion in normal rats

In order to assess the role of bile secretion in the serum cholestrol lowering effect of a portacaval anastomosis in rats, bile flow rate, bile salt and cholesterol secretion in bile were determined. The study comprised five groups of animals: (1) rats with protacaval shunt cholesterol free food ad libitum. (2) sham-operated and pair-fed controls; (3) unoperated, pair-fed controls; (4) unoperated controls on cholesterol free diet ad libitum; and (5) unoperated controls on normal laboratory rat chow ad libitum. Bile flow rate showed no difference in any of the groups on cholesterol free diet. Bile salt secretion was significantly elevated in shunted animals (87.1 +/- 7.0 nmol/min) as compared with pair-fed sham-operated (64.7 +/- 20.0 nmol/min) and unoperated controls (56.0 +/- 22.3 nmol/min). Biliary cholesterol output tended to be higher in shunted animals but this was not statistically significant. The data indicate that the atrophied rat liver in shunted animals is able to maintain a normal bile flow and to increase bile salt secretion. Thus, the serum cholesterol lowering action of a portocaval anastomosis may be partly due to an increased cholesterol catabolism to bile salts.