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Electromagnetic Fields in Biological Systems
where µ 0 is the magnetic permeability of vacuum. Dramatic demonstrations of these
forces can be seen when water is parted by an SMF of 4–8 T with a gradient of 50 T/m
(Ueno and Iwasaka 1994a,b). Magnetic levitation of diamagnetic materials such as wood
and other organic materials is realized in magnetic fields ≥20 T (Beaugnon and Tournier
1991). This phenomenon can also be explained by the principles of magnetic force: the
“force product” of maximum magnetic density and its maximum gradient. Moreover,
if magnetic forces are strong enough the repulsion of diamagnetic objects can balance
gravity, and objects levitated in this way can be held in stable equilibrium, apparently
violating Earnshaw’s theorem (Berryy and Geimz 1997). A variety of objects (one of
which was a living frog) was levitated in a magnetic force of about 1400 T 2 /m in 16 T.
The magnetic field effect observed with radical pair recombination is one of the
well-known mechanisms by which magnetic fields interact with biological systems.
Throughout the past decades there have been several experimental results describing
the effects of magnetic fields on radical pair recombination.
As reviewed recently by Ueno and Shigemitsu (2007), several biophysical and biochemical effects can be expected when biological systems are simultaneously exposed
to SMFs and other forms of energy such as light and radiation (Ueno and Harada 1986;
McLauchlan and Steiner 1991). Photochemical reactions produced by a radical pair
intermediate are expected to show SMF effects that arise from an electron Zeeman
interaction; an electron–nuclear hyperfine interaction (Fermi-contact interaction); or
a hyperfine interaction mechanism, such as an electron-exchange interaction in a radical pair intermediate (Hata 1976; Tanimoto et al. 1976, 1989; Schulten 1982a; Nagakura
and Molin 1992; Natarajan and Grissom 1997; Nagakura, Hayashi, and Azumi 1998;
Hayashi 2004).
Biological free radicals are most commonly oxygen or nitrogen based with an
unpaired electron, leading to them being known by the terms reactive oxygen species
(ROS), such as superoxide anion (O 2
− ), hydroxyl radical (OH•), and singlet oxygen ( 1 O 2 ),
or reactive nitrogen species (RNS), such as nitric oxide (NO) (Engström 2007). The ROS
and RNS play significant roles in immunological defense (Nathan 1992), intracellular
signaling (Lander 1997), and intercellular communication (Thannickal and Fanburg
2000) of biological systems. It is assumed that exposure to SMF can change the lifetime
of radical pairs and the yields of cage products (the yield of recombination reaction of
the radical pair in solvent cage) and escape products (the dissociated radicals outside
the solvent cage). If an SMF affects cells through the radical pair mechanism, an SMF
influences the spin of electrons in free radicals, which may lead to changes in chemical
reaction kinetics and alter cellular function (Brocklehurst and McLauchlan 1996). The
dependence of a reaction yield on an external magnetic field strength is called a MARY
spectrum (MARY stands for magnetically affected reaction yield) (Hayashi 2004).
Free radical reactions are ubiquitous in biology, and recent developments of the radical pair mechanism of low-field effects (≤1 mT), including the effects of SMFs and EMFs
(Schulten 1982b; Scaiano, Cozens, and McLean 1994; Brocklehurst and McLauchlan
1996; Timmel et al. 1998; Eveson et al. 2000; Brocklehurst 2002; Wang and Ritz 2006),
and the consideration of detailed biochemical and biophysical systems (Cintolesi et al.
2003; Liu et al. 2005; Efimova and Hore 2008) make this mechanism a prime candidate
for studying the effects down to the geomagnetic field strength, as recently reviewed by
Electromagnetic Fields in Biological Systems
where µ 0 is the magnetic permeability of vacuum. Dramatic demonstrations of these
forces can be seen when water is parted by an SMF of 4–8 T with a gradient of 50 T/m
(Ueno and Iwasaka 1994a,b). Magnetic levitation of diamagnetic materials such as wood
and other organic materials is realized in magnetic fields ≥20 T (Beaugnon and Tournier
1991). This phenomenon can also be explained by the principles of magnetic force: the
“force product” of maximum magnetic density and its maximum gradient. Moreover,
if magnetic forces are strong enough the repulsion of diamagnetic objects can balance
gravity, and objects levitated in this way can be held in stable equilibrium, apparently
violating Earnshaw’s theorem (Berryy and Geimz 1997). A variety of objects (one of
which was a living frog) was levitated in a magnetic force of about 1400 T 2 /m in 16 T.
The magnetic field effect observed with radical pair recombination is one of the
well-known mechanisms by which magnetic fields interact with biological systems.
Throughout the past decades there have been several experimental results describing
the effects of magnetic fields on radical pair recombination.
As reviewed recently by Ueno and Shigemitsu (2007), several biophysical and biochemical effects can be expected when biological systems are simultaneously exposed
to SMFs and other forms of energy such as light and radiation (Ueno and Harada 1986;
McLauchlan and Steiner 1991). Photochemical reactions produced by a radical pair
intermediate are expected to show SMF effects that arise from an electron Zeeman
interaction; an electron–nuclear hyperfine interaction (Fermi-contact interaction); or
a hyperfine interaction mechanism, such as an electron-exchange interaction in a radical pair intermediate (Hata 1976; Tanimoto et al. 1976, 1989; Schulten 1982a; Nagakura
and Molin 1992; Natarajan and Grissom 1997; Nagakura, Hayashi, and Azumi 1998;
Hayashi 2004).
Biological free radicals are most commonly oxygen or nitrogen based with an
unpaired electron, leading to them being known by the terms reactive oxygen species
(ROS), such as superoxide anion (O 2
− ), hydroxyl radical (OH•), and singlet oxygen ( 1 O 2 ),
or reactive nitrogen species (RNS), such as nitric oxide (NO) (Engström 2007). The ROS
and RNS play significant roles in immunological defense (Nathan 1992), intracellular
signaling (Lander 1997), and intercellular communication (Thannickal and Fanburg
2000) of biological systems. It is assumed that exposure to SMF can change the lifetime
of radical pairs and the yields of cage products (the yield of recombination reaction of
the radical pair in solvent cage) and escape products (the dissociated radicals outside
the solvent cage). If an SMF affects cells through the radical pair mechanism, an SMF
influences the spin of electrons in free radicals, which may lead to changes in chemical
reaction kinetics and alter cellular function (Brocklehurst and McLauchlan 1996). The
dependence of a reaction yield on an external magnetic field strength is called a MARY
spectrum (MARY stands for magnetically affected reaction yield) (Hayashi 2004).
Free radical reactions are ubiquitous in biology, and recent developments of the radical pair mechanism of low-field effects (≤1 mT), including the effects of SMFs and EMFs
(Schulten 1982b; Scaiano, Cozens, and McLean 1994; Brocklehurst and McLauchlan
1996; Timmel et al. 1998; Eveson et al. 2000; Brocklehurst 2002; Wang and Ritz 2006),
and the consideration of detailed biochemical and biophysical systems (Cintolesi et al.
2003; Liu et al. 2005; Efimova and Hore 2008) make this mechanism a prime candidate
for studying the effects down to the geomagnetic field strength, as recently reviewed by