Regulation of the Pore-Forming Activity of Cecropin A by Local Anesthetics

Abstract

The influence of local anesthetics on the regulation of the channel-forming activity of the antimicrobial peptide cecropin A has been investigated. The mean current flowing through the single cecropin channels isc was determined, and steady-state transmembrane current induced by cecropin AI∞ was measured. It has been shown that the introduction of 1 mM of bupivacaine, benzocaine or 0.3 mM of tetracaine into the membrane bathing solution results in a decrease in isc and I∞. At the same time, the addition of 1 mM lidocaine or procaine to the membrane-bathing solutions does not lead to a significant change in isc and I∞. Comparison of the absolute values and the sign of the change in the boundary potential of negatively charged membranes and relative changes of isc and I∞ after addition of local anesthetics shows that neither parameter correlates with the membrane boundary potential. The results of studying the effect of tested local anesthetics on the phase transition of membrane lipids allow us to conclude that the observed changes of isc and I∞ are due to modulation of the elastic properties of the membrane.