Electrical characteristics in an excitable element of lipid membrane

Kiyoshi Toko, Norimasa Ozaki, Satoru Iiyama, Kaoru Yamafuji, Yoshiko Matsui, Keiko Yamafuji, Minoru Saito, Masakazu Kato

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Abstract

Electrical characteristics in a membrane constructed from a porous filter adsorbed with a lipid analogue, dioleyl phosphate (DOPH), were investigated in a situation interposed between 100 mM NACl + 3 mM CaCl2 and 100 mM KCl. Calcium ions affected significantly the membrane characteristics. The membrane potential was negative on the KCl side, which implies the higher permeability to K+ than Na+; this tendency was increased by a tiny amount of Ca2+. While the membrane showed a low electrical resistance of several kΩ. cm2under K+/Na+ gradient, it showed several MΩ · cm2+ by Ca2+. The surface structure of the membrane exhibited many voids in the low-resistance state, but the surface was covered by oil droplets in the high-resistance state. Oscillations of the membrane potential appeared spontaneously with application of the electrical current from the KCl side to the NaCl + CaCl2 side. The frequency was increased with the electrical current. All these results were explained comprehensively using an electrochemical kinetic model taking account of the Ca2+ binding effect, where DOPH assemblies make a phase transition between oil droplets due to Ca2+ and multi-bilayers with excess K+. The oscillation arises from coupling of the phase transition to accumulation and release of K+ or Ca2+. This membrane can be used as an excitable element regulated by Ca2+ in neuro-computer devices.

Original languageEnglish
Pages (from-to)143-156
Number of pages14
JournalBiophysical Chemistry
Volume41
Issue number2
DOIs
Publication statusPublished - Nov 1991

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Organic Chemistry

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  • Cite this

    Toko, K., Ozaki, N., Iiyama, S., Yamafuji, K., Matsui, Y., Yamafuji, K., Saito, M., & Kato, M. (1991). Electrical characteristics in an excitable element of lipid membrane. Biophysical Chemistry, 41(2), 143-156. https://doi.org/10.1016/0301-4622(91)80014-I