Fig. 2.9. Sequence of morphological changes in a single frog nucleated erythrocyte exposed to very
low levels of electrical current. The same cell was photographed at intervals of 5 minutes,
demonstrating a change from the normal red cell type to a cell that has become round, lost all its
hemoglobin, and has major phase changes in its nucleus. These cells are quite alive, surviving in cell
culture and chemically demonstrating a marked increase in RNA content and a complete alteration in
protein composition.
In later experiments, Harrington (48) confirmed the original observation and determined that
while the RNA content of the changed cells was markedly increased, the DNA content remained
constant, and the protein composition changed markedly compared to the original normal cells-
changes that were consistent with the dedifferentiation process. He was also able to show that the direct
action of the electrical current was in the nature of a "trigger" stimulus at the level of the cell membrane
which then effected the dedifferentiation by means of the messenger RNA system. (Cells in which the
RNA protein mechanism was inhibited from acting by exposure to puromycin would not undergo
morphological alteration when exposed to adequate electrical current for an adequate amount of time.
However, if the current was then stopped and the puromycin washed out by several changes of media
the cells would then undergo dedifferentiation at the expected rate.) Pilla later confirmed these
observations and determined that the same dedifferentiation could be caused by exposure of the cells to
an appropriate pulsed magnetic field. In his view the primary effect of the electrical factors is a
perturbation of the Helmholtz outer layer (such as produced by a change in the ionic concentration or
the absorption of specific ions) on the cell membrane, with transmission of this information across the
membrane by charge transfer through molecules that span the membrane.
Therefore, in at least this one cell system, the nucleated erythrocyte, specific effects of low-level
direct currents have been observed and part of the mechanism involved in producing the effects has
been determined. The effect is a most profound one, involving the basic machinery of the cell and
ELECTROMAGNETISM & LIFE - 39