Effect of nerve impulses on the membrane potential of glial cells in the central nervous system of amphibia.

NEURONS AND G .LIAL CELLS in most parts of the nervo us system are intimately apposed, separated from each other by channels about 150 A. wide. It is natural to wonder whether the two types of cell influence one another either “electrically” (i.e., by current flow from one cell to the other) or by the release of a substance. It has been shown in the leech nervous system that if current is supplied to the interior of a nerve cell through an intracellular electrode, very little will enter the neighboring glial cell; most will pass through the intercellular clefts which have a relatively low resistance. Similarly, currents which flow during nerve impulses alter the membrane potential of the surrounding glia to a negligible extent good agreement with subsequent findings that the (10) clefts These results were in l between neurons and glial cells served as channels for the rapid diffusion of ions and of small molecules both in the leech and in amphibia (l&9). In the central nervous system of the leech, which contains smooth muscle cells in its connective tissue capsule, the effect of massive neuronal activity on the resting potential of glial cells could not be studied adequately because the preparation under these conditions and dislodged the electrode (1 0) . moved