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Local anesthetic tetracaine induces the interdigitation of lipid bilayers
International Congress Series 1283 (2005) 320 – 321
www.ics-elsevier.com
Local anesthetic tetracaine induces the interdigitation of lipid bilayers Shoji Kaneshina a,*, Hitoshi Matsuki a, Takashi Hata b, Hiroko Okuno a, Masataka Kusube a, Nobutake Tamai a a
Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan b Department of Material Science and Technology, Kochi National College of Technology, Nankoku, Kochi 783-8508, Japan
Abstract. A local anesthetic, tetracaine hydrochloride (TC) induced bilayer interdigitation of phosphatidylcholines containing various acyl chain lengths. The TC concentration necessary for the bilayer interdigitation was not consistent with the order of acyl chain length of phospholipids. Biphasic interactions for bilayer interdigitation were discussed. D 2005 Elsevier B.V. All rights reserved. Keywords: Interdigitation; Lipid bilayer; Local anesthetic; Membrane; Tetracaine
1. Introduction Recent studies on the phase transition of dipalmitoylphosphatidylcholine (DPPC) bilayer membrane suggested that there exists an interdigitated gel (LhI) phase induced by local anesthetics [1,2] as well as high concentration of alcohol. In the present study, the effect of a local anesthetic tetracaine hydrochloride (TC) on the bilayer phase behavior of a series of diacylphosphatidylcholines has been investigated by the differential scanning calorimetry (DSC).
* Corresponding author. Tel.: +81 88 6567513; fax: +81 88 6553162. E-mail address: [email protected] (S. Kaneshina). 0531-5131/ D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2005.07.025
S. Kaneshina et al. / International Congress Series 1283 (2005) 320–321
321
Fig. 1. Phase transition temperatures of lipid bilayer membranes as a function of tetracaine concentration. Bilayer phases: liquid crystal (La), ripple gel (PhV), lamellar gel (LhV) and interdigitated gel (LhI). (A) DMPC, (B) DPPC and (C) DSPC bilayers.
2. Materials and methods Synthetic lipids, dimyristoylphosphatidylcholine (DMPC), DPPC and distearoylphosphatidylcholine (DSPC) were obtained from Sigma-Aldrich Co. and used without further purification. The preparation of vesicle suspensions containing various TC concentrations and DSC measurement were the same as described previously [2]. Lipid concentration was kept at 2.0 mmol kg 1 through the experiments. 3. Results and discussion The phase-transition temperatures of DMPC, DPPC and DSPC bilayer membranes determined by DSC are shown in Fig. 1 as a function of TC concentration. Temperatures of main and pre-transitions were gradually depressed by an increase in TC concentration. The pre-transition disappeared at a concentration of TC; 6 mmol kg 1 for DMPC, 21 mmol kg 1 for DPPC and 10 mmol kg 1 for DSPC bilayers. Above the TC concentration at which the pretransition disappeared, the LhI phase appeared. The TC concentration necessary for the bilayer interdigitation varied irregularly and was not consistent with the order of acyl chain length of lipids. The action of TC on the induction of bilayer interdigitation may be attributable to two kinds of molecular interactions; (A) repulsive interaction between polar head groups and (B) van der Waals attractive interaction between hydrophobic chains of lipid molecules. Both interactions are not independent on each other. Interaction (B) affects interaction (A); the stronger the interaction (B), the weaker the interaction (A), and vice versa. Enhancement of interaction (A) by the addition of TC is responsible for the interdigitation in the DMPC bilayer. Contrarily, in the case of the DSPC bilayer, interaction (B) overcomes interaction (A) because of longer acyl chains of DSPC.
References [1] S. Maruyama, et al., Effects of pressure and local anesthetic tetracaine on dipalmitoylphosphatidylcholine bilayers, Biochim. Biophys. Acta 1325 (1997) 272 – 280. [2] T. Hata, H. Matsuki, S. Kaneshina, Effect of local anesthetics on the bilayer membrane of dipalmitoylphosphatidylcholine: interdigitation of lipid bilayer and vesicle–micelle transition, Biophys. Chemist. 87 (2000) 25 – 36.
www.ics-elsevier.com
Local anesthetic tetracaine induces the interdigitation of lipid bilayers Shoji Kaneshina a,*, Hitoshi Matsuki a, Takashi Hata b, Hiroko Okuno a, Masataka Kusube a, Nobutake Tamai a a
Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan b Department of Material Science and Technology, Kochi National College of Technology, Nankoku, Kochi 783-8508, Japan
Abstract. A local anesthetic, tetracaine hydrochloride (TC) induced bilayer interdigitation of phosphatidylcholines containing various acyl chain lengths. The TC concentration necessary for the bilayer interdigitation was not consistent with the order of acyl chain length of phospholipids. Biphasic interactions for bilayer interdigitation were discussed. D 2005 Elsevier B.V. All rights reserved. Keywords: Interdigitation; Lipid bilayer; Local anesthetic; Membrane; Tetracaine
1. Introduction Recent studies on the phase transition of dipalmitoylphosphatidylcholine (DPPC) bilayer membrane suggested that there exists an interdigitated gel (LhI) phase induced by local anesthetics [1,2] as well as high concentration of alcohol. In the present study, the effect of a local anesthetic tetracaine hydrochloride (TC) on the bilayer phase behavior of a series of diacylphosphatidylcholines has been investigated by the differential scanning calorimetry (DSC).
* Corresponding author. Tel.: +81 88 6567513; fax: +81 88 6553162. E-mail address: [email protected] (S. Kaneshina). 0531-5131/ D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2005.07.025
S. Kaneshina et al. / International Congress Series 1283 (2005) 320–321
321
Fig. 1. Phase transition temperatures of lipid bilayer membranes as a function of tetracaine concentration. Bilayer phases: liquid crystal (La), ripple gel (PhV), lamellar gel (LhV) and interdigitated gel (LhI). (A) DMPC, (B) DPPC and (C) DSPC bilayers.
2. Materials and methods Synthetic lipids, dimyristoylphosphatidylcholine (DMPC), DPPC and distearoylphosphatidylcholine (DSPC) were obtained from Sigma-Aldrich Co. and used without further purification. The preparation of vesicle suspensions containing various TC concentrations and DSC measurement were the same as described previously [2]. Lipid concentration was kept at 2.0 mmol kg 1 through the experiments. 3. Results and discussion The phase-transition temperatures of DMPC, DPPC and DSPC bilayer membranes determined by DSC are shown in Fig. 1 as a function of TC concentration. Temperatures of main and pre-transitions were gradually depressed by an increase in TC concentration. The pre-transition disappeared at a concentration of TC; 6 mmol kg 1 for DMPC, 21 mmol kg 1 for DPPC and 10 mmol kg 1 for DSPC bilayers. Above the TC concentration at which the pretransition disappeared, the LhI phase appeared. The TC concentration necessary for the bilayer interdigitation varied irregularly and was not consistent with the order of acyl chain length of lipids. The action of TC on the induction of bilayer interdigitation may be attributable to two kinds of molecular interactions; (A) repulsive interaction between polar head groups and (B) van der Waals attractive interaction between hydrophobic chains of lipid molecules. Both interactions are not independent on each other. Interaction (B) affects interaction (A); the stronger the interaction (B), the weaker the interaction (A), and vice versa. Enhancement of interaction (A) by the addition of TC is responsible for the interdigitation in the DMPC bilayer. Contrarily, in the case of the DSPC bilayer, interaction (B) overcomes interaction (A) because of longer acyl chains of DSPC.
References [1] S. Maruyama, et al., Effects of pressure and local anesthetic tetracaine on dipalmitoylphosphatidylcholine bilayers, Biochim. Biophys. Acta 1325 (1997) 272 – 280. [2] T. Hata, H. Matsuki, S. Kaneshina, Effect of local anesthetics on the bilayer membrane of dipalmitoylphosphatidylcholine: interdigitation of lipid bilayer and vesicle–micelle transition, Biophys. Chemist. 87 (2000) 25 – 36.