Micellar properties of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oyl taurine and relationship to in vitro red cell disruption.

Patients with a metabolic block in the conversion of THCA to cholic acid develop cirrhosis and hemolysis. Tauro-THCA has been shown to distort hepatic architecture and cause hemolysis in bile-fistula rats. In this study, the critical micellular concentration of tauro-THCA was found to be one fourth of that measured for the primary human bile salt, taurocholate. In short-term incubations with intact red cells, tauro-THCA was more effective than taurocholate in removing red cell membrane lipid, inducing morphological red cell sphering, and decreasing functional cellular membrane surface area. These detergent biological membrane effects were most apparent at a concentration above the critical micellar concentration, with the membrane toxicity of the two bile salts roughly paralleling their differences in critical micellar concentration. The lower critical micellar concentration, greater hydrophobicity, and enhanced surface-active properties of tauro-THCA are speculated on as possible factors contributing to the bile salt's toxicity in vivo.