Interaction of local anesthetics with lipid bilayers investigated by 1H MAS NMR spectroscopy

• Published in: Biochimica et biophysica acta 2012-12, Vol.1818 (12), p.3010-3018
• Main Authors: Weizenmann, Nicole, Huster, Daniel, Scheidt, Holger A.
• Format: Article
• Language: English
• Subjects: 1H NMR; Anesthetics, Local - metabolism; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Chemical shift; Dibucaine - metabolism; Hydrophobic and Hydrophilic Interactions; Intermolecular cross-relaxation; Lidocaine - metabolism; Lipid Bilayers - chemistry; Lipid Bilayers - metabolism; Local anesthetics; Magnetic Resonance Spectroscopy; Nuclear Overhauser enhancement spectroscopy; Procaine - metabolism; Tetracaine - metabolism
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2012.07.014

The membrane location of the local anesthetics (LA) lidocaine, dibucaine, tetracaine, and procaine hydrochloride as well as their influence on phospholipid bilayers were studied by 31P and 1H magic-angle spinning (MAS) NMR spectroscopy. The 31P NMR spectra of the LA/lipid preparations confirmed that the overall bilayer structure of the membrane remained preserved. The relation between the molecular structure of the LAs and their membrane localization and orientation was investigated quantitatively using induced chemical shifts, nuclear Overhauser enhancement spectroscopy, and paramagnetic relaxation rates. All three methods revealed an average location of the aromatic rings of all LAs in the lipid-water interface of the membrane, with small differences between the individual LAs depending on their molecular properties. While lidocaine is placed in the upper chain/glycerol region of the membrane, for dibucaine and procaine the maximum of the distribution are slightly shifted into the glycerol region. Finally for tetracaine the aromatic ring is placed closest to the aqueous phase in the glycerol/headgroup region of the membrane. The hydrophobic side chains of the LA molecules dibucaine and tetracaine were located deeper in the membrane and showed an orientation towards the hydrocarbon core. In contrast the side chains of lidocaine and procaine are oriented towards the aqueous phase. [Display omitted] ► Membrane location of 4 local anesthetics was studied by quantitative 1H MAS NMR. ► Aromatic rings of all local anesthetics are located in the lipid‐water interface. ► Small difference in the membrane location originate from molecular structures. ► Hydrophobic side chains of dibucaine and tetracaine are inserted into the membrane.