Abstract
The effects of the amide-linked (lidocaine (LDC), mepivacaine (MPV), prilocaine (PLC)) and ester-bound local anesthetics (benzocaine (BZC), procaine (PRC), and tetracaine (TTC)) on the pore-forming activity of the antifungal lipopeptide syringomycin E (SRE) in lipid bilayers were studied. Independently on electrolyte concentration in the membrane bathing solution the observed changes in conductance of SRE channels agreed with the altered membrane dipole potential under the action of ester-bound local anesthetics. Effects of aminoamides in diluted and concentrated solutions were completely different. At 0.1 M KCl (pH 7.4) the effects of amide-linked anesthetics were in accordance with changes in the membrane surface potential, while at 2 M KCl aminoamides blocked ion passage through the SRE channels, leading to sharp reductions in pore conductance at negative voltages and 100-fold decreases in the channel lifetimes. The effects were not practically influenced by the membrane lipid composition. The interaction cooperativity implied the existence of specific binding sites for amide-bound anesthetics in SRE channels.
Highlights
Local anesthetics are compounds causing the suspension of impulse transmission along nerve fibers, and their molecular structure comprises hydrophobic and lipophilic parts connected by amide or ether bonds
In addition to modifying the elastic properties of membranes, anesthetics electrostatically interact with the lipid bilayer, i.e., the drugs alter the electrical potential at the water/lipid boundary[17], termed the membrane boundary potential
We previously showed that local anesthetics affect the boundary potential of model lipid membranes
Summary
Local anesthetics are compounds causing the suspension of impulse transmission along nerve fibers, and their molecular structure comprises hydrophobic and lipophilic parts connected by amide or ether bonds. They are divided into amide-linked (e.g., LDC, MPV, and PLC) and ester-bound (e.g., BZC, PRC, and TTC) groups. The authors concluded that uncharged TTC disorders myristoyl chains, while the charged form induces the formation of an interdigitated gel phase. The authors concluded that TTC increases surface potential more effectively than LDC37 Both the charged and uncharged forms of TTC and LDC induce substantial changes in the membrane dipole potential[38,39]
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