AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 3 482-R487, Copyright © 1984 by American Physiological Society
"Functional polarity" of the spinal cord caused by its longitudinal electric dipole moment
H. Athenstaedt
Specific reactions of the vertebrates that occur through lengthwise
application of direct-current (DC) electric fields in the spinal cord and
are dependent on the direction of the current (e.g., electric narcosis and
electric excitation) can be explained by the existence of a longitudinal
dipole moment in the spinal cord. The relationship between "functional
polarity of the spinal cord" and its longitudinal dipole moment was
established in two different experimental series. 1) Reactions of
functional polarity were quantitatively tested on Amphioxus (lancelet) and
on numerous Teleostei. On this point the findings of other researchers were
confirmed and complemented. 2) Fresh, almost-live spinal cord preparations
(cow) were quantitatively tested using pyroelectric (PE) methods. A
longitudinal electric dipole moment was demonstrated along the entire
length of the white matter. Moreover fresh spinal cord preparations showed
a polar orientation on sudden temperature change in a high-voltage DC
field. The PE behavior showed a pronounced electric field dependence.
Because the white matter is largely composed of longitudinally arranged
nerve fibers, individual axons may also have a longitudinal electric dipole
moment. Consequently one might expect the following: polar orientation of
the growing neurite by an applied DC field, an electric dipole field inside
and outside the axon, and a transport of charge carriers along the lines of
flux of this dipole field. Moreover PE and piezoelectric (PZE) properties
of the neuron should be provable.
