71
2
Pulsed Electric Fields
in Biological Cells
and Membranes
2.1 Introduction ............................................................ 71
2.2 Interaction of Electric Fields with
Living Cells .............................................................. 73
2.3 Modeling Electric Fields in Cells ......................... 76
Continuum Mean-Field Approaches for Spherical
Cells • Continuum Approaches Applied to More
Complicated Cell Geometries • Models of Electric
Field Interactions in Tissues and Nerves
2.4 Temperature Changes Due to
Electric Pulsing ....................................................... 94
2.5 Role of the Biological Dielectric Properties ........ 97
2.6 Extracting Parameters from
R. P. Joshi
Cell Suspensions ................................................... 102
K. H. Schoenbach
References .......................................................................... 105
2.1 Introduction
The interaction of electric and magnetic fields with biological systems has been a
persistent scientific interest over the past two decades (Blank 1995; Polk and Postow
1996). Applications and mechanistic understanding have continued to receive growing
a ttention in this arena due to issues relating to therapies, health risks and hazards, biosensing, and medical delivery technologies. Biological sensory systems can detect very
weak steady fields. For example, variations as small as a few percentage of the Earth’s
magnetic field (5 × 10 −5 T) can be detected (Lohmann and Lohmann 1996), while sharks
and rays sense extremely weak electric fields in seawater. However, the effects of weak
fields are difficult to understand and any possible role in triggering or coordinating
coupled biophysical mechanisms in organized cell systems is challenging to analyze.
Thus, molecular changes or signaling induced by low fields can be difficult to extract
and discern from other sources of change such as natural biochemical pathways. By
2
Pulsed Electric Fields
in Biological Cells
and Membranes
2.1 Introduction ............................................................ 71
2.2 Interaction of Electric Fields with
Living Cells .............................................................. 73
2.3 Modeling Electric Fields in Cells ......................... 76
Continuum Mean-Field Approaches for Spherical
Cells • Continuum Approaches Applied to More
Complicated Cell Geometries • Models of Electric
Field Interactions in Tissues and Nerves
2.4 Temperature Changes Due to
Electric Pulsing ....................................................... 94
2.5 Role of the Biological Dielectric Properties ........ 97
2.6 Extracting Parameters from
R. P. Joshi
Cell Suspensions ................................................... 102
K. H. Schoenbach
References .......................................................................... 105
2.1 Introduction
The interaction of electric and magnetic fields with biological systems has been a
persistent scientific interest over the past two decades (Blank 1995; Polk and Postow
1996). Applications and mechanistic understanding have continued to receive growing
a ttention in this arena due to issues relating to therapies, health risks and hazards, biosensing, and medical delivery technologies. Biological sensory systems can detect very
weak steady fields. For example, variations as small as a few percentage of the Earth’s
magnetic field (5 × 10 −5 T) can be detected (Lohmann and Lohmann 1996), while sharks
and rays sense extremely weak electric fields in seawater. However, the effects of weak
fields are difficult to understand and any possible role in triggering or coordinating
coupled biophysical mechanisms in organized cell systems is challenging to analyze.
Thus, molecular changes or signaling induced by low fields can be difficult to extract
and discern from other sources of change such as natural biochemical pathways. By