Comparative effects of short chain alcohols on lipid phase transitions.

We have been systematically investigating the physical interactions of alcohols with synthetic lipids in order to elucidate the mechanisms of alcohol intoxication. It has previously been shown that the effects of ethanol on the phase transition temperatures of saturated chain phosphatidylcholines (PC's) are biphasic [11]. The secondary high concentration effect has recently been shown to be due to a transition to a new completely interdigitated state [16]. In the present report we have investigated the influence of the chain length of the alcohol on the induction of this interdigitated state. We demonstrate that all three alcohols have a biphasic effect on the transition temperature of PC, and the comparison of the concentration dependencies of this effect for the three alcohols provides some insight into the possible mechanism of the transition. The potential biological importance of this secondary alcohol-membrane interaction is discussed.