Induction of cell proliferation and vasoconstriction by low density lipoprotein

Hyperlipidemia and hypertension are risk factors for cardiovascular diseases. To obtain insight into intracellular mechanisms underlying these phenomenon, the influence of low density lipoprotein (LDL) on the intracellular free calcium concentration, the intracellular pH, the calcium influx as well as proliferation rate of cultured vascular smooth muscle cells was studied. 1-15 micrograms/ml of LDL increased dose-dependently the concentration of intracellular free calcium and led to biphasic pH-shifts. 3-7 micrograms/ml of LDL augmented thymidine incorporation into cell DNA by 70% and enhanced calcium influx by 80%. LDL (1-15 micrograms/ml) clearly increased contractile response of aortic rings. The findings indicate that low concentrations of LDL may contribute to the pathogenesis of cardiovascular diseases by enhancing cell proliferation and vasoconstriction via changing intracellular calcium and intracellular pH.