Ab initio SCF study of the effect of Na+ and K+ ions and water on the local anaesthetic-phospholipid interaction

Abstract

For gaining insight into the interactions of local anaesthetics with phospholipids, ab initio molecular orbital calculations were performed using trimethylamine and phosphate as model substances. The (OH)2OPO-···H+N(CH3)3 interaction was found comparable in strength to the (OH)2OPO-···M+ (M = Na, K) interaction and considerably stronger than the (OH)2OMPO···H2O interaction. This suggests that a major role of local anaesthetics may consist in their disturbing the P-O···H2O hydrogen bonds. Such interference may be one of the possible types of interaction between local anaesthetics and the biophase, leading to a measurable pharmacological effect.