A role for PKCβ in altering calcium homeostasis under hyperglycemic conditions in human endothelial cells
Cardiovascular diseases (CVD) are leading causes of morbidity and mortality for diabetic patients. Endothelial cell dysfunction is a hallmark of CVD. Intracellular Ca2+ concentration ([Ca2+]i) may regulate endothelial cell function. Here, we investigated the effects of hyperglycemia on [Ca2+]i and a role for protein kinase C (PKC) in regulating [Ca2+]i in the human endothelial cell line, EA.hy926. Cells were cultured in normal (5.5 mM, NG) or high (25 mM, HG) glucose media then treated with either a) vehicle (0.1% DMSO), b) LY341684 (selective PKC? inhibitor, 100 nM, 24h), or c) phorbol 12-myristate 13-acetate (PMA, PKC activator, 200 nM, 4h). Using a spectrofluorometer, [Ca2+]i in cells loaded with Fura 2-AM was monitored in the absence of extracellular Ca2+. Thapsigargin (SERCA inhibitor, 1 ?M,) induced a transient increase in [Ca2+]i which was similar among the experimental groups of cells. However, when 1.5 mM Ca2+ was added, Ca2+ entry was significantly increased in cells cultured in HG compared to NG. This elevated Ca2+ entry in HG-treated cells was attenuated by treatment with LY341684. Cells treated with PMA in NG showed an increased Ca2+ entry similar to cells cultured in HG. Our results suggest that hyperglycemia enhanced Ca2+ entry in endothelial cells is PKC? dependent. Thus, PKC? inhibitors may restore normal endothelial cell function under hyperglycemic conditions. Supported by NIH/NIDCR.
A role for PKCβ in altering calcium homeostasis under hyperglycemic conditions in human endothelial cells.
FASEB Journal, 26(Supp 1),