A comparison of the effect of bile salts on maximal hepatic excretion of certain organic anions in the rabbit under urethane and pentobarbitone.

The influence of two different anaesthetics, sodium pentobarbitone and ethyl urethane, on the enhancement of maximal bilirubin and bromosulphthalein (BSP) excretion induced by bile salts was investigated in rabbits. Two micelle-forming (glycodeoxycholate and taurocholate) and one non-micelle-forming (dehydrocholate) bile salts were used. Under urethane anaesthesia the bile flow was lower than with pentobarbitone, and this could be attributed to a smaller bile salt non-dependent fraction of secretion. The effect of bile salts on the maximal excretion of the two organic anions appeared more clearly related to some kind of micelle interaction in rabbits anaesthetized with urethane than in pentobarbitone-anaesthetized animals. Thus, under urethane, infusions of glycodeoxycholate substantially increased the maximal excretion of bilirubin and BSP, taurocholate exerted an intermediate and dehydrocholate only a small effect. Under pentobarbitone, however, the augmenting action of all three bile salts was similar. The influence of bile salts on the endogenous excretion of bile pigments in experiments in which the test anion was BSP showed corresponding differences dependent upon the anaesthetic used. Possible explanations for those results are discussed.