Ionic excitation of a clone of mouse neuroblastoma

The electrical properties and the possible regulation of these properties were studied by means of intracellular microelectrode recordings in cells of mouse neuroblastoma clone N1E-115. This clone has high levels of tyrosine hydroxylase and regulates this enzyme. Cells treated for 24 h with 4 μM aminopterin followed by at least 5 days in culture developed rhythmic discharge of action potentials when superfused with phosphate-buffered saline containing ≤ 0.2 mM calcium or ≤ 0.2 mM calcium and zero potassium. This ionic excitation occurred in no cells at less than 5 days after treatment with aminopterin but at 5 days or more after treatment, 20% of cells responded to low calcium while 52% responded to low calcium and zero potassium. Concomitant with the development of a susceptibility to ionic excitation was an increase in the average resting membrane potential and morphologic maturation. This ionic excitation of cultured mouse neuroblastoma cells may be useful for studying biochemical events associated with repetitive discharge of action potentials.