Anestésicos locais: interação com membranas de eritrócitos de sangue humano, estudada por ressonância magnética nuclear de ¹H e 31P

Abstract

Recebido em 2/4/03; aceito em 7/8/03 LOCAL ANESTHETICS: INTERACTION WITH HUMAN ERYTHROCYTE MEMBRANES AS STUDIED BY 1 H AND 31 P NUCLEAR MAGNETIC RESONANCE. The literature carries many theories about the mechanism of action of local anesthetics (LA). We can highlight those focusing the direct effect of LA on the sodium channel protein and the ones that consider the interaction of anesthetic molecules with the lipid membrane phase. The interaction between local anesthetics and human erythrocyte membranes has been studied by 1 H and 31 P nuclear magnetic resonance spectroscopy. It was found that lidocaine (LDC) and benzocaine (BZC) bind to the membranes, increase the mobility of the protons of the phospholipid's acyl chains, and decrease the mobility and/or change the structure of the polar head groups. The results indicate that lidocaine molecules are inserted across the polar and liquid interface of the membrane, establishing both electrostatic (charged form) and hydrophobic (neutral form) interactions. Benzocaine locates itself a little deeper in the bilayer, between the interfacial glycerol region and the hydrophobic core. These changes in mobility or conformation of membrane lipids could affect the Na +-channel protein insertion in the bilayer, stabilizing it in the inactivated state, thus causing anesthesia.

Growth, Shrinking, and Breaking of Pluronic Micelles in the Presence of Drugs and/or β-Cyclodextrin, a Study by Small-Angle Neutron Scattering and Fluorescence Spectroscopy

“…Considering the structure of lidocaine (Scheme ), the LD benzene group is most probably inside the apolar region of the micelle with the substituents protruding into the water shell. Previous studies using UV spectroscopy have indeed reported limited partitioning of LD inside the F127 micellar core, and FTIR studies have shown that uncharged local anesthetics are mainly located in the membrane/water interface, competing with the polar heads of phospholipids in binding with water molecules. , …”