Combined effects of magnetic fields and temperature changes on 1-aminonaphthalene-8-sulfonic acid fluorescence in red blood cell ghost cell membrane

Abstract

In the present study, we performed an experiment to clarify the possible effects of magnetic fields of up to 8 T on cell membrane fluidity by using red blood cell ghosts and a fluorescence dye, 1-aminonaphthalene-8-sulfonic acid (ANS). The time course of ANS emission at 480 nm under the influence of a magnetic field at 5 T was observed. The effects of multiple rapid temperature changes and magnetic fields were investigated. The emission intensity at 480 nm increased when the temperature of the cell holder was increased from 20 to 38–46 °C for 15 min. A change in temperature exhibited an increase in the fluidity of the lipid molecules in the cell membrane and increased the population of ANS molecules emitting light at 480 nm in the cell membrane, which is hydrophobic. A discontinuous change in fluorescence at 38–40 °C was exhibited under exposure to a magnetic field at 5 T, while the temperature dependency was continuous without exposure to the magnetic field. In addition, under exposure to the magnetic field, the fluorescence during a decrease in temperature from 38 to 20 °C remained at a level close to the fluorescence during an increase in temperature. The results indicated that the fluidity of the molecules in the cell membrane was decelerated by exposure to magnetic fields at 5 T. We speculated that the magnetic orientation in a part of the lipid membrane disturbed the release of ANS molecules from a hydrophobic region of the membrane.