The formation of macrophage foam cells, which is the key event in
atherosclerosis, occurs by the uptake of
oxidized low-density lipoprotein (
Ox-LDL) via the
scavenger receptor (CD36) pathway. Ca(2+) plays an important role in
atherosclerosis. However, in the spatiotemporal view, the correlation between kinetic changes of intracellular-free
calcium ([Ca(2+)](i)) and the cellular dysfunctions in the formation of macrophage foam cells has not yet been studied in detail. By the use of confocal
laser scanning microscope and flow cytometer, we have detected Ca(2+) dynamics, the assembly of
F-actin, and the expression of CD36 under the exposure of U937-derived macrophages to
Ox-LDL. The uptake of
Ox-LDL significantly increased [Ca(2+)](i) in U937-derived macrophages in both acute and chronic treatments (P<0.01). In particular, the increases of the induced [Ca(2+)](i) were different in the presence or absence of extracellular Ca(2+) under acute exposure. A time-dependent rise in
F-actin assembly and CD36 expression at 12 and 24h was induced, respectively, by
Ox-LDL. The spatiotemporal increases of [Ca(2+)](i) induced by
Ox-LDL probably have the key effect on the early phrase in the formation of macrophage foam cells.