[Insulinemia, fatty acids in plasma lipids and lipoproteins and oxidation of VLDL and LDL in hyperlipidemia].

Both insulin resistance and hyperlipidaemia are connected with an increased oxidative stress, playing a significant role in the development of atherosclerosis. A significant event in the process being the oxidative modification of the lipoproteins, especially LDL. Aim of the study was to analyse relationships between the fatty acid composition of the plasma cholesteryl esters (CE), triglycerides (TG) and phosphatidylcholine (PC) and of the separated LDL, insulinaemia and oxidability of both VLDL and LDL particles. We have observed the group of 75 patients with hyperlipidaemia (52 men and 23 women), which was divided in the two subgroups after the basal insulinaemia (more resp. less than 13 mU/l). Fasting hyperinsulinaemia of the probands with normal glucose tolerance served as a marker of an insulin resistance. Patients with both hyperlipidaemia and basal hyperinsulinaemia were characterized by a significantly higher concentration of TG, apolipoprotein B in LDL, and lower concentration of cholesterol in HDL, especially in HDL3. We have observed only marginally significant elevation of concentration of the dihomo-gammalinolenic acid (DGLA) in plasma PC and also higher concentrations of alpha-linolenic and lower of arachidonic acid (AA) and in LDL-CE in the hyperinsulinaemic group. We have also found significantly positive correlations between the stearic acid in plasma PC, alpha-linolenic acid in plasma TG on one hand and the basal insulinaemia on the other hand. Significant positive correlation was also found between the ratio docosahexaenoic/docosapentaenic acid and insulinaemia in 120 min of oral glucose tolerance test. Significant negative correlation was observed between the ratio AA/DGLA and basal insulinaemia. Analysing the lipoperoxidation of VLDL and LDL using the method of conjugated diene kinetics we have found statistically non-significant decrease of lag phase duration of LDL and VLDL (their oxidability).