The lipid composition of serum lipoproteins in the harbour seal, Phoca vitulina

Abstract

1. 1. The density profile of serum lipoproteins and their lipid composition was studied in 12 adult, female harbour seals. The animals were sampled after an approximate 20 hr fast. 2. 2. The density profile of lipoproteins showed that the harbour seals displayed a distinct VLDL (density <1.006 g/ml) and HDL band (density about 1.125 g/ml), but no clear LDL band. There was a rather diffuse population of lipoproteins in the density range of 1.019–1.100 g/ml. 3. 3. Mean serum total cholesterol concentration was 5.7 mmol/l; about 60% of this cholesterol was located in the HDL fraction (density > 1.063 g/ml). 4. 4. The fasted seals were found to carry 4% of serum total lipids in chylomicrons. These lipoproteins consisted of 51% of triacylglycerols (on the basis of total chylomicron lipids). 5. 5. The LDL (defined as heparin-manganese precipitable lipoproteins in VLDL and chylomicron-deficient serum) contained 49% of cholesterol and 43% of phospholipids (on the basis of total LDL lipids). 6. 6. The HDL (defined as heparin-manganese soluble lipoproteins in VLDL and chylomicron-deficient serum) contained 36% of cholesterol and 58% of phospholipids (on the basis of total HDL lipids).