[期刊论文]

出版年：1984

The permeation of the lipophilic ion dipicrylamine through planar lipid membranes formed from dipalmitoylphosphatidylcholine in n-decane shows an anomaly near the main phase transition of this system. Both the rate constant, ki, of ion translocation across the membrane interior and the interfacial concentration, N, of this ion have a maximum at about 36°C. Analogous experiments were performed with tetraphenylborate. A considerably lesser effect of the phase transition was found. The addition of cholesterol leads to a broadening of the maxima for ki and N. The time course of the current following a voltage jump shows a characteristic change below a temperature of about 45°C, if the molar ratio cholesterol/ phosphatidylcholine in the membrane forming solution exceeds 1. While the current transient decays exponentially above 45°C, a sum of two exponential terms yields an adequate fit below that temperature. This is regarded as evidence for a lateral phase separation below 45°C into structurally different domains, which provide two different pathways for dipicrylamine.

Phase transition;Phase separation;Cholesterol;Dipicrylamine;(Lipid bilayer) ;