Affinity labels for membrane components involved in the uptake of bile acids and of phallotoxins by hepatocytes. Development of covalently binding derivatives of bile acids and of compounds related to cholecystographic agents.

Abstract

A series of covalently binding derivatives of bile acids, fusidic acid and of compounds similar to cholecystographic agents were synthesized. Nearly all of them inhibited the development of protrusions on the surface of isolated hepatocytes regularly seen after treatment with phalloidin. The same compounds inhibited the uptake of demethylphalloin and of cholate in a concentration dependent manner. Two kinds of effects could be distinguished: The irreversible part of the inhibition depended on the incubation period and could not be removed by washing procedures. The reversible one was independent on the duration of the preincubation. Final results indicated that the tested derivatives inhibited either both transports, and the phalloidin response of liver cells to the same degree and in the same manner, or were found to be ineffective in all tests. The above parallelism supports the hypothesis that phallotoxins may be translocated by a carrier system normally responsible for the uptake of bile acids from the portal blood.