Iron overload in hypercholesterolemic rats affects iron homeostasis and serum lipids but not blood pressure

Epidemiologic and experimental data suggest that excess iron may contribute to the development of cardiovascular diseases (CVD). Because increased LDL cholesterol, decreased HDL cholesterol and alteration of systolic blood pressure (SBP) have all been implicated as risk factors for atherosclerosis and related CVD, the present study was designed to determine whether excess iron alters serum lipids and SBP in control and hypercholesterolemic rats. Female Fischer rats were divided into four groups. The control group (C) was fed the control diet, the Cl group was fed the control diet and given iron dextran injections, the hypercholesterolemic group (H) was fed a 1 g/100 g cholesterol diet, and the HI group was fed the cholesterol diet and given iron dextran injections. The rats were fed the diets for 8 wk and iron dextran injections were given during wk 6 at doses of 10 mg/d for 5 d. Excess iron reduced (P < 0.01) plasma total cholesterol in rats fed the cholesterol diet (5.31 +/- 0.83 and 3.17 +/- 0.31 mmol/L for H and HI], respectively). Excess iron also resulted in a redistribution of cholesterol among the various lipoprotein fractions, with an increase (P < 0.01) in HDL cholesterol (0.56 +/- 0.12 and 0.85 +/- 0.16 mmol/L for H and HI, respectively) and a decrease (P < 0.01) in LDL cholesterol (4.49 +/- 0.77 and 2.09 +/- 0.26 mmol/L for H and HI, respectively). This redistribution also occurred in the rats fed the control diet. The treatments did not affect SBP or heart rate. The high cholesterol diet affected iron homeostasis; group H had lower transferrin saturation than group C (P < 0.01); group HI had a lower serum iron concentration than group Cl but did not differ from group H (P < 0.05). Therefore, we conclude that if iron has any effect on CVD, it is not through its influence on serum lipids and blood pressure.