AJP - Cell Physiology, Vol 233, Issue 1 56-C60, Copyright © 1977 by American Physiological Society
Application of a solid membrane ion-selective electrode to in vivo measurements
W. Crowe, A. Mayevsky and L. Mela
A solid membrane electrode containing a highly selective ion-complexing
agent immobilized in a polymer membrane is applied to measurements in vivo
from the surface of an organ. For the measurements reported here, an
ion-complexing agent selective for potassium is incorporated in a silicone
rubber membrane and applied to measure ion changes in the brain. Comparison
is made to the measurements recorded with an ion-selective microelectrode
in the cortical tissue. The surface electrode compares favorably with the
microelectrode in terms of amplitude of response and response time for the
changes seen in the phenomenon of cortical spreading depression of Leao.
The methods reported here are amenable to a selection of ion measurements
by incorporation of a suitable ion exchanger in a polymer membrane.
Extracellular ion activity is monitored in the anesthetized animal by
holding the electrode in a balanced suspension which provides a light,
flexible contact to the organ of interest. In the unanesthetized animal,
when recording from the brain, the electrode is fixed in a skull-implanted
cannula.
