Oxidized low density lipoprotein inhibits bradykinin‐induced phosphoinositide hydrolysis in cultured bovine aortic endothelial cells

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Abstract
Vascular endothelial cells, in response to various neurohumoral and physical stimuli, produce an endothelium‐derived relaxing factor, a substance which regulates vascular tone. We have demonstrated that oxidized low density lipoprotein (LDL) inhibits endothelium‐dependent relaxation. We studied the effect of oxidized LDL on inositol phosphates formation stimulated with bradykinin (BK) in cultured bovine aortic endothelial cells. BK elicited a rapid generation of inositol phosphates from inositol phospholipids. Accumulation of inositol 1,4,5‐trisphosphate (IP3) stimulated with BK (0.1 μM) was markedly inhibited by oxidized LDL. However, native LDL had little effect on BK‐induced accumulation of IP3. From these results, oxidized LDL inhibits receptor‐mediated phosphoinositides hydrolysis and modulates the endothelial function.