European Biophysics Journal

, Volume 34, Issue 5, pp 461–468 | Cite as

The influence of static magnetic fields on mechanosensitive ion channel activity in artificial liposomes

  • Steven Hughes
  • Alicia J. El Haj
  • Jon Dobson
  • Boris Martinac


The influence of static magnetic fields (SMFs) on the activity of recombinant mechanosensitive ion channels (the bacterial mechanosensitive ion channel of large conductance—MscL) following reconstitution into artificial liposomes has been investigated. Preliminary findings suggest that exposure to 80-mT SMFs does not induce spontaneous MscL activation in the absence of mechanical stimulation. However, SMFs do appear to influence the open probability and single channel kinetics of MscL exposed to negative pipette pressure. Typical responses include an overall reduction in channel activity or an increased likelihood of channels becoming “trapped open” in sub-conducting states following exposure to SMFs. There is a delay in the onset of this effect and it is maintained throughout exposure. Generally, channel activity showed slow or limited recovery following removal of the magnetic field and responses to the magnetic were often reduced or abolished upon subsequent exposures. Pre-exposure of the liposomes to SMFs resulted in reduced sensitivity of MscL to negative pipette pressure, with higher pressures required to activate the channels. Although the mechanisms of this effect are not clear, our initial observations appear to support previous work showing that the effects of SMFs on ion channels may be mediated by changes in membrane properties due to anisotropic diamagnetism of lipid molecules.


Magnetic field Mechanosensitive ion channel of large conductance 



We would like to thank Albert Raso and Thom Nguyen for technical assistance. This work was supported by a grant from the Australian Research Council, a Wellcome Trust Showcase Award and a Ph.D. studentship from the UK Engineering and Physical Sciences Research Council. J.D. acknowledges the support of a Wolfson Foundation/Royal Society Research Merit Award.


  1. Baroske E, Helfrich W (1978) Magnetic anisotropy of egg lecithin membranes. Biophys J 24(3):863–868PubMedGoogle Scholar
  2. Baureus Koch CL, Sommarin M, Perrson BR, Salford LG, Ebehardt JL (2003) Interaction between weal low frequency magnetic fields and cell membranes. Bioelectromagnetics 24(6):395–402CrossRefPubMedGoogle Scholar
  3. Bras W, Diakun GP, Diaz JF, Maret G, Krammer H, Bordas J, Medrano FJ (1998) The susceptibility of pure tubulin to high magnetic fields: A magnetic biofrigence and X-ray fibre diffraction study. Biophys J 74:1509–1521Google Scholar
  4. Cardon TB, Tiburu EK, Lorigan GA (2003) Magnetically aligned phospholipid bilayers in weak magnetic fields: optimisation, mechanism, and advantages for X-band EPR studies. J Magn Reson 161:77–90CrossRefPubMedGoogle Scholar
  5. Dobson J, Stewart Z, Martinac B (2002a) Preliminary evidence for weak magnetic field effects on mechanosensitive ion channel sub-conducting states in E. coli . Electromagnetic Biol Med 21:89–95CrossRefGoogle Scholar
  6. Dobson J, Stewart Z, Martinac B (2002b) preliminary evidence for weak magnetic field effects on mechanosensitive ion channel sub-conducting states in E. coli–errata. Electromagnetic Biol Med 21:309–309Google Scholar
  7. Häse CC, Le Dain AC, Martinac B (1995) Purification and functional reconstitution of the recombinant large mechanosensitive ion channel (MscL) of Escherichia coli. J Biol Chem 270:18329–18334Google Scholar
  8. Hamill OP, Martinac B (2001) Molecular basis of mechanotransduction in living cells. Physiol Rev 81:685–740PubMedGoogle Scholar
  9. Iwasaka M, Ueno S, Tsuda H (1994) Effects of magnetic fields on fibrinolysis. J Appl Phys 75:105–107Google Scholar
  10. Maret G, Dransfeld K (1997) Macromolecules and membranes in high magnetic fields. Physica 86b:1077–1083Google Scholar
  11. Martinac B (2004) Mechanosensitive ion channels: molecules of mechanotransduction. J Cell Sci 117:2449–2460CrossRefPubMedGoogle Scholar
  12. Perozo E, Kloda A, Cortes DM, Martinac B (2002) Physical principles underlying the transduction of bilayer deformation forces during mechanosensitive channel gating. Nat Struct Biol 9:696–703CrossRefPubMedGoogle Scholar
  13. Rosen AD (1992) Magnetic field influence on acetylcholine release at the neuromuscular junction. Am J Physiol 262(6:1):1418–1422Google Scholar
  14. Rosen AD (1993a) A proposed mechanism for the action of strong static magnetic fields on biomembranes. Int J Neurosci 73(1–2):115–119PubMedGoogle Scholar
  15. Rosen AD (1993b) Membrane response to static magnetic fields: effect of exposure duration. Biochim Biophys Acta 1148(2):317–320PubMedGoogle Scholar
  16. Rosen AD (1996) Inhibition of calcium channel activation in GH3 cells by static magnetic fields. Biochim Biophys Acta 1282(1):149–155PubMedGoogle Scholar
  17. Rosen AD (2003a) Mechanism of action of moderate-intensity static magnetic fields on biological systems. Cell Biochem Biophys 39:163–173CrossRefPubMedGoogle Scholar
  18. Rosen AD (2003b) Effect of a 125 mT static magnetic field on the kinetics of voltage activated Na+ channels in GH3 cells. Bioelectromagnetics 24(7):517–523CrossRefPubMedGoogle Scholar
  19. Rosen MS, Rosen AD (1990) Magnetic field influence on paramecium motility. Life Sci 46(21):1509–1515CrossRefPubMedGoogle Scholar
  20. St. Pierre TG, Dobson J (2000) Theoretical evaluation of cell membrane ion channel activation by applied magnetic fields. Eur Biophys J 29:455–456Google Scholar
  21. Sanders CR, Hare BJ, Howard KP, Prestegard JH (1994) Magnetically orientated phospholipid micelles as a tool for the study of membrane associated molecules. Prog NMR Spectrosc 26:421–424CrossRefGoogle Scholar
  22. Scholz F, Boroske E, Helfrich W (1984) Magnetic anisotropy of lecithin membranes. A new anisotropy susceptometer. Biophys J 45(3):589–592Google Scholar
  23. Speyer JB, Sripada PK, Das Gupta SK, Shipley GG (1987) Magnetic orientation of sphinogomyelin-lecithin bilayers. Biophys J 51:687–691Google Scholar
  24. Torbet J, Ronziere M (1984) Magnetic alignment of collagen during self assembly. Biochem J 219:1057–1059PubMedGoogle Scholar

Copyright information

© EBSA 2005

Authors and Affiliations

  • Steven Hughes
    • 1
  • Alicia J. El Haj
    • 1
  • Jon Dobson
    • 1
  • Boris Martinac
    • 2
  1. 1.Medical Research Unit, Institute of Science and Technology in MedicineKeele University Hartshill, Stoke-on-TrentUK
  2. 2.School of Medicine and PharmacologyUniversity of Western AustraliaCrawleyAustralia

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