SODIUM, CALCIUM AND LATE POTASSIUM CURRENTS ARE REDUCED IN CEREBELLARGRANULE CELLS CULTURED IN THE PRESENCE OF A PROTEIN COMPLEX CONFERRING RESISTANCE TO EXCITATORY AMINO-ACIDS

Whole-cell, patch-clamp recordings were used to study voltage-gated cu rrents generated by cerebellar granule cells that were cultured in med ium containing either 10% fetal calf serum (hereafter termed S+ granul es) or neurite outgrowth and adhesion complex (NOAC, hereafter called NOAC granules). NOAC is a protein complex found in rabbit serum that r enders granules resistant to the excitotoxic action of excitatory amin o acids. During depolarizing commands both S+ and NOAC granules genera ted Na+ and Ca2+ inward currents and an early and a late K+ outward cu rrents. However, Na+ and Ca2+ inward currents and late outward K+ curr ents recorded in NOAC granules were smaller than those seen in S+ gran ules. Furthermore, although of similar amplitude, early K+ currents di splayed different kinetics in the two types of neurons. Thus, these da ta demonstrate that the electrophysiological properties of cerebellar granules, and probably of other neuronal populations, depend upon seru m components and raise the possibility that an analogous modulation mi ght be operative in vivo, and play a role in development, synaptic pla sticity or neuropathological processes.