Potassium and calcium channel dependence of bursting in cultured neuronal networks.

Increases in extracellular potassium concentrations reliably increase burst rates in cultured fetal murine spinal cord networks. This effect could be mimicked by either blocking voltage-gated potassium conductances or facilitating excitatory synaptic interactions, but not by blocking specific calcium-dependent potassium conductances or tonic depolarization. Spontaneous bursting in cultured networks is apparently dependent on potassium currents and intracellular calcium levels, but not on the pharmacologically characterized calcium-dependent potassium conductances.