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

We examined serum specimens collected in the fasting and postprandial states from five X-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 (VLDLfuge), LDL, (LDLfuge) and HDL (HDLfuge) fractions. VLDLfuge was compared with VLDL cholesterol concentration estimated as serum triglyceride concentration divided by four (VLDLtrig). HDLfuge was compared with cholesterol remaining in the supernatant after precipitation of apolipoprotein B-containing lipoproteins with Mn2+ and heparin (HDLppt). LDLfuge was compared with the concentration determined from the Friedewald formula (total cholesterol less HDLppt less VLDLtrig). After correcting the centrifuged fractions for recovery of total cholesterol, the mean difference between the LDLfriede and LDLfuge of fasting samples was <5% and the mean difference between fasting HDLppt and HDLfuge was <8%. Fasting VLDLtrig was more than twice VLDLfuge, 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. (C) 2000 Elsevier Science Inc.