Elevation of intracellular Ca 2+ concentration in rabbit nonpigmented ciliary epithelial cells by allicin

Abstract

A previous study has shown that allicin produces changes in aqueous humor dynamics, and this study was conducted to examine possible cellular mechanisms. In rabbit nonpigmented ciliary epithelial cells, basal levels of [Ca 2+], were determined to be 164 ± 34 nM. Allicin, a sulfhydryl-reactive agent, induced Ca 2+ transients at 0.01 mM and at 0.2 mM, the Ca 2+ transient peaked at 732 ± 35 nM. Allicin-induced Ca 2+ transients were prevented by pretreatment with dithiothreitol which did not affect the basal Ca 2+ levels. Allicin had only a slight, insignificant, effect on L-type Ca 2+ currents, and allicin-induced Ca 2+ transients were also present under extracellular Ca 2+-free conditions. These data suggest that intracellular Ca 2+ stores are the most probable source of allicin's effect. Pretreatment of cells with ryanodine, an inhibitor of Ca 2+-induced-Ca 2+-release, inhibited allicin-induced Ca 2+ transients, but the basal Ca 2+ levels were unaffected by ryanodine. Thus, allicin-induced Ca 2+ transients are most likely mediated through ryanodine-sensitive intracellular Ca 2+ stores.