THE INTRACELLULAR TRACER NEUROBIOTIN ALTERS ELECTROPHYSIOLOGICAL PROPERTIES OF RAT NEOSTRIATAL NEURONS

During whole-cell recordings from rat neostriatal neurons with Neurobi otin-filled patch-clamp electrodes, we observed markedly prolonged act ion potentials. Similar long-lasting action potentials were not detect ed when the tracer was omitted from the pipette solution. Resting memb rane potential and input resistance remained unchanged in the presence of the tracer. The investigation of this effect revealed that Neurobi otin decreased the threshold for calcium spike generation probably by blocking a potassium conductance activated by depolarisation or by a d irect action on calcium channels. The effect of Neurobiotin displayed a fast onset and was not observed during intracellular recordings usin g conventional microelectrodes. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.