Calcium agonist (BayK 8644) augments voltage-sensitive calcium currents but not synaptic transmission in cultured mouse spinal cord neurons.

The effects of the calcium agonist, BayK 8644, and other agents upon voltage-dependent calcium conductance (VSCC) and evoked synaptic activity were studied in cultured mouse spinal cord and dorsal root ganglion neurons. As expected, BayK 8644 increased the VSCC corresponding to L channels. It had relatively little effect on evoked synaptic activity; the small but statistically significant effect that was noted was a decrease. Nitrendipine had either no effect or an increase with no statistically significant effect being seen with regard to synaptic activity over the population sampled. An increased extracellular Ca++ concentration increased both VSCC and synaptic activity. We conclude that VSCC with L channel properties are probably not involved in transmitter release produced by action potentials in the central synapses occurring in the dissociated mouse spinal cord cell culture system.