L-aspartic acid induces a region of negative slope conductance in the current-voltage relationship of cultured spinal cord neurons

Individual murine spinal cord neurons were grown in dissociated tissue cultures. Using either one or two conventional intracellular microelectrodes neurons were voltage-clamped and current-voltage (I–V) curves were constructed using command pulses. l-Aspartic acid was then applied and I–V curves repeated in the presence of this excitatory amino acid. l-Aspartic acid induced a region of negative slope conductance (RNSC) in the steady-state I–V relationships of these neurons. Such a RNSC accounts for the apparent reduction of conductance observed in response to excitatory amino acids 5,7,8 and its instability likely contributes to the electrogenesis of bursting in central neurons.