[Intracellular signal transmission of low density lipoprotein receptors in human monocytes].

The authors found that in human monocytes administered low density lipoprotein in doses of 50 micrograms had optimal inhibition of endogenous cholesterol synthesis which measured by [14C] acetate incorporation. There was not effect of pertussis toxin and phorbol myristate acetate on the inhibiton of endogenous cholesterol synthesis, whereas calcium channel blocker verapamil and phospholipase A2-inhibitor chloroquine decreased it. In contrast, the protein kinase C-stimulant phorbol myristate acetate alone had effects as LDL, but the protein kinase C-inhibitor H-7 had antagonist effect against LDL. Inositol phosphate generation was induced by administration of LDL in doses of 50 micrograms, which was pertussis toxin insensitive. The calcium signal was not also pertussis toxin sensitive, while occurred an intensive protein kinase C activation by administration of LDL. In signal transduction of monocytes activated by LDL may be an important role of the opening of calcium channels and activation of two enzymes, such as phospholipase A2 and protein kinase C.