[Establishment and implication of an assay for high density lipoprotein phospholipids in human serum]

To develop an assay for high density lipoprotein phospholipids in human serum based on ascorbutate reduction method.

HDLs were separated from apolipoprotein B-containing lipoproteins by precipitation of phosphotungstic acid and magnesium chloride. Phospholipids of HDL were extracted by ethanol/ether, and dried. After the dried phospholipids were digested by sulphuric acid and perchloric acid, the color was developed by adding ammonium molybdate in ascorbutate. The levels of high density lipoprotein phospholipids (HDL-PL) were measured by spectrophotometry at 700 nm.

The coefficients of variation (CV) were 3.6% and 3.7% within two batches of assays. Recovery of isolated HDL-PL added to serum ranged from 98% to 107%, averagely 103%. The established assay for human serum HDL-PL was used to measure the serum levels of 30 hypercholesterolemic subjects, 30 hypertriglyceridemic subjects, 30 combined hyperlipidemic subjects, and 30 normolipidemic subjects. The hypertriglyceridemic subjects had lower HDL-PL level than normolipidemic subjects and hypercholesterolemic subjects (The P values are 0.005 and 0.007 respectively).

A simple and specific method for assay of HDL-phos-pholipids in human serum has been developed. The above data collected by the use of this method demonstrate the closer relationship between human HDL-PL metabolism and triglyceride metabolism, suggesting that lower HDL-PL level might serve as an index in the assay for type IV hyperlipidemia.