Kinetic analysis of LDL oxidation in IHD and IHD risk subjects in Indian population

High plasma concentration of low-density lipoprotein (LDL) is associated with increased risk of atherosclerosis. Modified forms of LDL, especially oxidized LDL play a major role in its pathogenesis. This article gives detailed insight into the kinetics ofin vitro LDL oxidation by copper at different concentrations in normal and high-risk group subjects. Basal level of oxidatively modified LDL was significantly higher in ischaemic heart disease (IHD) and IHD hyperlipidemic subjects compared to normolipidemic and, hyperlipidemic control subjects, respectively. Derivatization of amino groups of apo-lipoprotein as monitored by estimating free amino groups concentration, was significantly higher in high-risk group and established IHD cases. Kinetics of oxidation was studied with two different concentrations of CuSO(4) (2.5 mM and 7.5 mM). thiobarbituric acid reactive substances (TBARS) level increases with time, and up to 95% oxidation was observed in 8 hr. About 60-65% less free amino groups were observed in native-LDL isolated from IHD patients compared to normal subjects. Study also showed an increase in two oxidative products studied, 20α-OH-cholesterol and 4-cholesten-3-one with oxidation time accompanied by corresponding decrease in LDL cholesterol. Increase in oxidative species was more evident in high-risk group and IHD patient. Basal level of oxidatively modified LDL measured in terms of TBARS was significantly higher in present study, strongly support that the extent of LDL oxidation monitored as TBARS and FAG level in circulating-LDL could be used as risk marker for high risk group.