RÉSUMÉ

On rat retinal preparation in whole-cell mode retinal ganglion cells (RGC) tonic firing induced calcium signals were recorded and their modulation by Kv3 potassium channels was studied. RGC depolarization with 500 ms current steps caused tonic action potentials (AP) generation and development of calcium signals which amplitude depended quite linearly on mean AP frequency with mean slope (1.4 ± 0.2) s·nmol/l (n = 5). The calcium signals mean tau of decay value was (6.8 ± 1.4) s (n = 5). After application of tetraethylammoniun (500 μM), which in such a concentration blocks Kv3.1/Kv3.2 potassium channels, decreasing of firing frequency, increasing of AP width and decreasing of fast afterhyperpolarization amplitude were observed. In the blocker presence the calcium signal amplitude vs mean AP frequency dependency slope mean value increased to (2.1 ± 0.3) s·nmol/l. The calcium signals decay not changed significantly, the mean value was (8.9 ± 1.6) s (n = 5). Thus, voltage-dependent Kv3.1/Kv3.2 potassium channels, which play a key role in tonic firing pattern generation in RGC, also modulate appropriate calcium signals and prevent the cells from significant intracellular calcium increasing and its possible cytotoxic action.