Adhesion interactions of neurons in a tissue may affect the ion conductance of the plasma membrane inducing selective localization and modulation of channels. We studied the adhesion region of cultured neurons from rat hippocampus as a defined model where such effects could be observed electrophysiologically, taking advantage of extracellular recording by a transistor integrated in the substrate. We observed the K+ current through the region of soma adhesion under voltage- clamp and compared it with the current through the whole cell. We found that the specific A-type conductance was depleted, even completely, in the region of adhesion whereas the specific K-type conductance was enhanced up to a factor of twelve. The electrophysiological approach opens a new way in investigating targeting of ion channels in the cell membrane in function of adhesion processes.
Fig. 2.:Neurons from rat hippocampus cultured for 4 days in serum free medium on a silicon chip with a silica surface coated with poly-L- lysine. Scanning electron micrograph. Scale bar 10 µm. The linear array of open transistors is seen in the center with the drains and the lanes of field oxide directed upwards and with the common source at the bottom.
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