| Abstract: | Dissociated mouse neuroblastoma cells were studied in vitro by using intracellular microelectrodes for electrical stimulation and recording. Some, but not all cells, which exhibited well developed action potentials to electrical stimulation also showed changes in membrane potential to iontophoretically applied acetylcholine (ACh). The types of responses to ACh varied. Short latency depolarizing responses to pulses of ACh (similar to those obtained with skeletal muscle) as well as sustained depolarization to steady ACh application (D response) occurred. A longer latency prolonged hyperpolarizing response (H response) and bi- and triphasic combinations of H and D responses were also seen. Pairs of cells showing morphologic contact were tested for the occurrence of effective synaptic coupling by placing intracellular microelectrodes in each cell. In none of 95 cases tested did spike activity produced by direct electrical stimulation of one cell elicit a synaptic potential of 200 μv or more in the other. |
