首页 | 本学科首页   官方微博 | 高级检索  
     


Dissociation equilibrium between uncharged and charged local anesthetic lidocaine in a surface-adsorbed film
Authors:Hitoshi?Matsuki  author-information"  >  author-information__contact u-icon-before"  >  mailto:matsuki@bio.tokushima-u.ac.jp"   title="  matsuki@bio.tokushima-u.ac.jp"   itemprop="  email"   data-track="  click"   data-track-action="  Email author"   data-track-label="  "  >Email author,Michio?Yamanaka,Hiroshi?Kamaya,Shoji?Kaneshina,Issaku?Ueda
Affiliation:(1) Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minamijosanjima-cho, 770-8506 Tokushima , Japan;(2) Department of Chemistry, Faculty of Science, Kyushu University , 4-2-1 Ropponmatsu, Chuo-ku, 810-8560 Fukuoka, Japan;(3) Department of Anesthesia, Department of Veterans Administration Medical Center and University of Utah School of Medicine, Salt Lake City, UT 84148, USA
Abstract:The dissociation equilibrium between uncharged local anesthetic lidocaine (LC) and charged local anesthetic LC (LCbullH+) in a surface-adsorbed film was investigated by measuring the surface tension and pH of aqueous solutions of a mixture of hydrochloric acid and LC. The surface tension values decreased slightly with increasing total molality mt at 0leX2le0.5, where X2 is the mole fraction of LC in the mixture, while they decreased rapidly with increasing mt at 0.5<X2le1. It was shown from the pH measurements that almost all LC molecules were changed into LCbullH+ ions by protonation at 0leX2le0.5 and both forms coexisted only at 0.5<X2le1. The quantities of the respective LC and LCbullH+ transferred from the aqueous solution to the adsorbed film, i.e., their surface densities, were calculated by applying the thermodynamic equations derived to the surface tension and pH data. A greater quantity of LC than LCbullH+ existed in the adsorbed film at the coexisting composition. The partitioning behavior of LC and LCbullH+ in the adsorbed film was characterized by three composition regions: (1) slight partitioning of low surface-active LCbullH+ in the region at 0leX2le0.5, (2) preferential partitioning of LC at 0.5<X2H+ at around 0.7leX2le1. The present results clearly indicate that uncharged local anesthetics transfer into hydrophobic environments such as cell membranes more than charged ones.
Keywords:Surface tension  Surface-adsorbed film  Uncharged local anesthetic  Charged local anesthetic  Preferential partitioning  Negative adsorption
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号