Activation of NMDA receptors linked to modulation of voltage-gated ion channels and functional implications.

Autor: Davis, S.F., Linn, C.L.
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Zdroj: American Journal of Physiology: Cell Physiology; Mar2003, Vol. 284 Issue 3, pC757, 12p, 24 Graphs
Abstrakt: Catfish (Ictalurus punctatus) cone horizontal cells contain N-methyt-D-aspartate (NMDA) receptors, the function of which has yet to be determined. In the present study, we have examined the effect of NMDA receptor activation on voltage-gated ion channel activity. NMDA receptor activation produced a long-term downregulation of voltage-gated sodium and calcium currents but had no effect on the delayed rectifying potassium current. NMDA's effect was eliminated in the presence of AP-7. To determine whether NMDA receptor activation had functional implications, isolated catfish cone horizontal cells were current clamped to mimic the cell's physiological response. When horizontal cells were depolarized, they elicited a single depolarizing overshoot and maintained a depolarized steady state membrane potential. NMDA reduced the amplitude of the depolarizing overshoot and increased the depolarized steady-state membrane potential. Both effects of NMDA were eliminated in the presence of AP-7. These results support the hypothesis that activation of NMDA receptors in catfish horizontal cells may affect the type of visual information conveyed through the distal retina. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index