title: Effects of the local anesthetic benzocaine on the human erythrocyte membrane and molecular models.
abstract: The interaction of the local anesthetic benzocaine with the human erythrocyte membrane and molecular models is described. The latter consisted of isolated unsealed human erythrocyte membranes (IUM), large unilamellar vesicles (LUV) of dimyristoylphospatidylcholine (DMPC), and phospholipid multilayers of DMPC and dimyristoylphospatidyletanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Optical and scanning electron microscopy of human erythrocytes revealed that benzocaine induced the formation of echinocytes. Experiments performed on IUM and DMPC LUV by fluorescence spectroscopy showed that benzocaine interacted with the phospholipid bilayer polar groups and hydrophobic acyl chains. X-ray diffraction analysis of DMPC confirmed these results and showed that benzocaine had no effects on DMPE. The effect on sodium transport was also studied using the isolated toad skin. Electrophysiological measurements indicated a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of benzocaine, reflecting inhibition of active ion transport.
authors.affiliation: Faculty of Chemical Sciences, University of Concepcion, Casilla 160-C, Concepcion, Chile. msuwaslk@udec.cl
authors.forename: Mario
authors.initials: M
authors.lastname: Suwalsky
authors.forename: Carlos
authors.initials: C
authors.lastname: Schneider
authors.forename: Fernando
authors.initials: F
authors.lastname: Villena
authors.forename: Beryl
authors.initials: B
authors.lastname: Norris
authors.forename: Hernán
authors.initials: H
authors.lastname: Cárdenas
authors.forename: Francisco
authors.initials: F
authors.lastname: Cuevas
authors.forename: Carlos P
authors.initials: CP
authors.lastname: Sotomayor
mesh_terms: D000779:Anesthetics, Local / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001001:Anura; D001566:Benzocaine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D004594:Electrophysiology; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008858:Microscopy, Phase-Contrast; D008958:Models, Molecular; D015394:Molecular Structure; D012879:Skin Physiological Phenomena; D014961:X-Ray Diffraction
chemical_list: D000779:Anesthetics, Local; D001566:Benzocaine