Fractional turnover of apolipoprotein(a) and apolipoprotein B-100 within plasma lipoprotein(a) particles in statin-treated patients with elevated and normal Lp(a) concentration

Abstract

<i>Context:</i> Lipoprotein(a) [Lp(a)] is a highly atherogenic lipoprotein characterized by apolipoprotein(a) [apo(a)] covalently bounded to apoB-100 (apoB). However, the metabolism of apo(a) and apoB within plasma Lp (a) particles in patients on statins remains unclear.<br/> <i>Methods:</i> The kinetics of Lp(a)-apo(a) and Lp(a)-apoB were determined in 20 patients with elevated Lp (a) (≥0.8 g/L; n=10) and normal Lp(a) (≤0.3 g/L; n=10) using stable isotope techniques and compartmental modeling. Plasma apo(a) concentration wasmeasured using liquid chromatography–mass spectrometry. All patients were on statin therapy and were studied in the fasting state.<br/> <i>Results:</i> The fractional catabolic rate (FCR) of Lp(a)-apo(a)was not significantly different fromthat of Lp(a)-apoB in statin-treated patients with elevated or normal Lp(a) (P N 0.05 in both). Lp(a)-apo(a) FCR was significantly correlated with Lp(a)-apoB in patients with elevated and normal Lp(a) concentrations (r = 0.970 and r = 0.979, respectively; all P b 0.001) with Lin's concordance test showing substantial agreement between the FCRs of Lp(a)-apo(a) and Lp(a)-apoB in patients with elevated and normal Lp(a) concentrations (r_c = 0.978 and r_c = 0.966, respectively).<br/> <i>Conclusion:</i> Our data indicate that the apo(a) and apoB proteins within Lp(a) particles have similar FCR and are therefore tightly coupled as an Lp(a) holoparticle in statin-treated patients with elevated and normal Lp (a) concentrations.