Modulation of voltage-dependent calcium channels by glutamate in rat cerebellar granule cells in culture.

Voltage-dependent calcium channels of cerebellar granule cells maintained in a Ca(2+)-free depolarising solution were recorded using the cell-attached configuration of the patch-clamp technique. An increase in the maximum open probability of calcium channels and a shift in their activation curve toward more hyperpolarizing potentials were found in the presence of glutamate, a natural, excitatory amino acid. Such an increase in the activity of calcium channels was not due to ionic fluxes activated by glutamate, and was probably produced by a second messenger pathway triggered by the binding of glutamate to its receptor.