[Determination of cholesterol in lipoprotein fractions by agarose gel electrophoresis]

Abstract

Objective: To evaluate a single step electrophoresis for quantitative determination of cholesterol of high-, low-, very-low-density lipoprotein(HDL, LDL, VLDL) and fast pre-beta lipoprotein [lipoprotein (a), Lp(a)].

Methods: Quantification of lipoprotein cholesterol was performed by enzymatic staining of cholesterol in a new agarose gel electrophoresis method that allows the separation of LDL, VLDL, HDL, and Lp(a) by Helena REP system. The results of electrophoresis method were compared with those by traditional method like PTA-Mg2+ precipitation method for HDL-C, PVS precipitation method for LDL-C, and Immunoturbidimetric assay(ITA) method for Lp(a).

Results: Within-runs CV were 5.16%-7.46%, 1.26%-3.28% and 3.78%-5.86% for VLDL-C, LDL-C and HDL-C, respectively. Between-runs CV were 8.35%-11.25%, 2.78%-4.08% and 4.23%-6.36%, respectively. The linearity of this method was up to 10.35 mmol/L total cholesterol. The recoveries were 90.3%, 94.3% and 89.6%, respectively. No interference were observed when bilirubin(< 342 mumol/L), hemoglobin(< 20 g/L) or triglyceride(< 11.0 mmol/L) were added to pooled serum, respectively. There was good agreement between methods, with r = 0.9557 for HDL-C(electrophoresis method vs PTA-Mg2+ precipitation method), r = 0.9609 for LDL-C(electrophoresis method vs PVS precipitation method) and r = 0.9235 for Lp(a)-C (electrophoresis method) vs Lp(a) (ITA method).

Conclusions: The electrophoresis method offers a simple and inexpensive means of simultaneously measuring HDL-C, VLDL-C, Lp(a)-C and LDL-C.