The electrical properties of the SK-N-SH human neuroblastoma cell were studied by standard intracellular recording techniques; the average resting membrane potential was -21 ± 11 mV, with a few cells showing mebrane potentials greater than - 40 mV. Under standard tissue culture conditions, as used in these experiments, less than 1% of these cells show morphological differentiation (process formation). In response to current injection, a variety of graded responses with a relatively slow rise time were observed. In some cells only delayed rectification was observed. In no instance did current injection result in a characteristic action potential. An analogous method for determining electrical excitability was to measure 22Na influx in the presence and absence of a depolarizing agent, veratridine (0.1 mM). In such experiments, the influx of 22Na in SK-N-SH cells was only slightly altered by veratridine. Taken together, these data suggest that the morphologically undifferentiated human neuroblastoma cells are relatively inexcitable electrically. The iontophoretic application of acetylcholine to the cell body produced depolarizing responses whose amplitudes were dependent on the membrane potential.
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