Involvement of calcium in retinal pigment epithelial cell proliferation and pigmentation

Purpose. The aim of this study is to explore the role of intracellular calcium in the mechanism of co-regulation of retinal pigment epithelial cells (RPE) by vitreous fluid and platelet mitogens, in order to evaluate the use of calcium modulating drugs in preventing RPE cell proliferation and contraction of fibrocellular membranes.Methods. Monolayers of human RPE cells were loaded with Fura-2-AM and examined in a fluorimeter for changes in intra-cellular free calcium in response to platelet mitogens (PDG-FAB or TGFβ1) and vitreous fluid (containing vitreous substrate proteins), both alone or in combination. The effect of the calcium antagonists TMB8 and verapamil and the calmodulin antagonists J8 and tamoxifen were then examined on RPE cell proliferation and pigmentation, both in the presence and absence of vitreous substrate and platelet mitogens.Results. We report that co-exposure of RPE cells to platelet mitogens and vitreous fluid produces an increase in intracellular free calcium of greater duration ...