Odorants are known to suppress non-selectively voltage-gated currents in olfactory receptor cells. We found that odorants also suppress voltage-gated currents in neurons of outside of the olfactory system. Under voltage clamp, odorants such as amyl acetate, limonene, and acetophenone suppressed non- selectively voltage-gated currents (a Ca2+ current, a delayed rectifier K+ current, a fast transient K+ current, and an anomalous rectifier K+ current) in horizontal cells from the goldfish retina. An amyl acetate puff completely and immediately suppressed the Ca2+ current (I(Ca)) and the delayed rectifier K+ current induced by repetitive depolarizations, suggesting that amyl acetate is a closed-channel blocker. Odorants did not change significantly the activation curve of I(Ca), but made the slope of inactivation curve of I(Ca) gentler and shifted its half-inactivation voltage toward a negative voltage. These results are similar to the effects of odorants on voltage-gated currents in olfactory receptor cells. This suggests that odorants may suppress the voltage-gated currents in retinal horizontal cells by the same mechanism described in olfactory receptor cells. (C) 2000 Elsevier Science Ireland Ltd.
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