Determination of fasting and postprandial lipoprotein cholesterol concentrations in pigs: A comparison of methods

Abstract

We examined serum specimens collected in the fasting and postprandial states from five 8-week-old Large White pigs to determine whether cholesterol fractions can be estimated without use of the ultracentrifuge. Sequential ultracentrifugation was used to determine cholesterol in VLDL (VLDL fuge), LDL (LDL fuge) and HDL (HDL fuge) fractions. VLDL fuge was compared with VLDL cholesterol concentration estimated as serum triglyceride concentration divided by four (VLDL trig). HDL fuge was compared with cholesterol remaining in the supernatant after precipitation of apolipoprotein B-containing lipoproteins with Mn 2+ and heparin (HDL ppt). LDL fuge was compared with the concentration determined from the Friedewald formula (total cholesterol less HDL ppt less VLDL trig). After correcting the centrifuged fractions for recovery of total cholesterol, the mean difference between the LDL friede and LDL fuge of fasting samples was <5% and the mean difference between fasting HDL ppt and HDL fuge was <8%. Fasting VLDL trig was more than twice VLDL fuge, after correction for cholesterol recovery, possibly because of very low recoveries in the ultracentrifuge or because of an incorrect divisor of total serum triglyceride. We conclude that whereas HDL and LDL cholesterol can be reliably estimated in these specimens by simple methods, VLDL cholesterol estimation requires further investigation. A secondary finding was that feeding significantly reduced the concentrations of total cholesterol and LDL cholesterol but raised HDL cholesterol.