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

We examined serum specimens collected in the fasting and postprandial state s from five X-week-old Large White pigs to determine whether cholesterol fr actions can be estimated without use of the ultracentrifuge. Sequential ult racentrifugation was used to determine cholesterol in VLDL (VLDLfuge), LDL, (LDLfuge) and HDL (HDLfuge) fractions. VLDLfuge was compared with VLDL cho lesterol concentration estimated as serum triglyceride concentration divide d by four (VLDLtrig). HDLfuge was compared with cholesterol remaining in th e supernatant after precipitation of apolipoprotein B-containing lipoprotei ns with Mn2+ and heparin (HDLppt). LDLfuge was compared with the concentrat ion determined from the Friedewald formula (total cholesterol less HDLppt l ess VLDLtrig). After correcting the centrifuged fractions for recovery of t otal 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 corre ction for cholesterol recovery, possibly because of very low recoveries in the ultracentrifuge or because of an incorrect divisor of total serum trigl yceride. We conclude that whereas HDL and LDL cholesterol can be reliably e stimated in these specimens by simple methods, VLDL cholesterol estimation requires further investigation. A secondary finding was that feeding signif icantly reduced the concentrations of total cholesterol and LDL cholesterol but raised HDL cholesterol. (C) 2000 Elsevier Science Inc.