Voltage-Operated Calcium Currents in Retinal Ganglion Cells of the Rat Eye

Using a voltage-clamp technique in the whole-cell configuration, we studied voltage-operated calcium currents in retinal ganglion cells (RGCs) obtained from the rat eye. In all examined cells, we recorded high-threshold calcium currents with the mean maximum amplitude 285 +/- 33 pA (104-593 pA; n = 22) at the membrane potential -10 to 0 mV. In a considerable part of the neurons (10 of 22; 45%), we also observed low-threshold calcium currents (published data on the presence of such currents in mammalian RGCs are contradictory). The mean maximum amplitude of the latter (low-threshold) currents was 99 +/- 11 pA (54-157 pA; n - 10) at the membrane potential -35 mV. The observed differences in the patterns of voltage-dependent calcium currents in various RGCs can be related to functional differentiation of these cells.