Role of Ca2+ store in AMPA-triggered Ca2+ dynamics in retinal horizontal cells.

Fura-2 fluorescent calcium imaging was applied to measure [Ca(2+)](i) in freshly dissociated horizontal cells of carp retina, and a model containing endoplasmic reticulum (ER) membrane processes and plasma membrane processes was constructed for quantitative analyses of the AMPA-triggered calcium dynamics. A transient increase followed by a sustained steady level of [Ca(2+)](i) was observed when 100 microM AMPA was applied, while the initial transient increase of [Ca(2+)](i) was suppressed by exogenously applied ryanodine. The model analyses results suggest that the AMPA-triggered calcium dynamics involves a number of cytoplasmic and endoplasmic processes that interact with each other. It also suggests that calcium store is an important part contributing to the transient calcium signal.