Effects of fluvastatin treatment on red blood cell Na+ transport systems in hypercholesterolemic subjects

This study was performed to ascertain the effects of short-term cholesterol-lowering therapy with fluvastatin on red blood cells Na+ transport systems. Forty familial hypercholesterolemic subjects (FH; 19 men and 21 women) without hypertension or cardiovascular disease were given a placebo for 4 weeks, and then randomized in two groups. Twenty (fluvastatin group) were given fluvastatin (40 mg/day), and the other 20 (placebo group) continued placebo administration. After the placebo period and after 4 and 12 weeks of placebo or fluvastatin treatment, we measured Na+/K+ pump activity, Na+/K+ cotransport (Na+/K+ Ct), Na+/Li+ countertransport (Na+/Li+ Cnt), passive Na+ permeability (Na+PP), and internal Na+ content (Na+i). The same parameters were measured in 23 control subjects (C) with normal cholesterolemic values, who were matched for sex and age. FH had higher Na+/Li+ Cnt values than C (193.2 +/- 59.4 vs. 139.8 +/- 48.7 microM cells/h; p < 0.01), an increase in Na(+)PP (0.034 +/- 0.012/h vs. 0.018 +/- 0.004/h; p < 0.001), and higher Na(+)i (7.5 +/- 1.5 vs. 6.2 +/- 0.9 mM cells; p < 0.001). In hypercholesterolemic subjects, Na(+)i values were correlated with cholesterol (total and LDL) and apo B levels, whereas an inverse correlation was found for HDL-c and apo AI levels. Reduced total and LDL cholesterol and apo B levels after fluvastatin treatment caused a decrease in both Na(+)/Li(+) Cnt (from 186.1 +/- 60.5 to 125.1 +/- 34.0 microM cells/h; p < 0.001) and Na(+) PP (from 0.035 +/- 0.013/h to 0.02 +/- 0.016/h; p < 0.01), and an increase in Na+/K+ pump activity (from 1,549.0 +/- 507.7 to 1,894.2 +/- 536.2 microM cells/h; p < 0.04), with a significant reduction in the internal Na+ content (from 7.5 +/- 1.6 to 5.8 +/- 2.4 mM cells; p < 0.001). Our findings show that hypercholesterolemia affects red blood cell Na+ transport systems, with an increase in Na+/Li+Cnt, Na+PP, and the internal Na+ content. Cholesterol-lowering treatment with fluvastatin influences Na+ transport systems and reduces the internal Na+ content. This might also be responsible for the greater vascular reactivity observed in hypercholesterolemic patients, and its amelioration after a reduction in cholesterol levels.