The inhibitory effect of nilvadipine on calcium channels in retinal ganglion cells in goldfish.

PURPOSE: Our aim was to examine the inhibitory effect of nilvadipine on voltage-gated calcium (Ca) channels in solitary ganglion cells. METHODS: Eyes were excised from goldfish. Ganglion cells were enzymatically dissociated from isolated retina. Whole-cell currents were recorded with the perforated-patch clamp technique. RESULTS: Depolarizing step pulses to more than -48 mV evoked a slowly inactivating inward Ca current. The current-voltage relation for the nilvadipine-sensitive current was bellshaped, and the peak current reached a maximum at -8 mV in the presence and absence of nilvadipine. Nilvadipine block of voltage-gated Ca current was dose-dependent between 1 and 100 microM. The half-maximum inhibitory dose was 35 microM. CONCLUSIONS: The inhibitory effect of orally administered nilvadipine on Ca channels had a mild influence in ganglion cells.