The mechanism of liposomal damage by taurocholate.

The stability of small unilamellar vesicles formed by egg-yolk phosphatidylcholine (PC) has been examined in the presence of sodium taurocholate. The permeability of the vesicular membrane changes as the total taurocholate concentration increases, until a transformation from mixed bile salt/PC vesicles to mixed micelles occurs. Based on experiments in which the bile salt-induced release of either hydrophilic (carboxyfluorescein) or hydrophobic (Bromothymol blue) probes was studied, and on fluorescence polarization of the probe 1,6-diphenyl-1,3,5-hexatriene and turbidity measurements, a two-step process for the initial stage of liposomal damage by taurocholate is postulated.