Plasma content of cholesterol and glycerol alcohols depends on the number of fatty acid double bonds in lipoprotein lipid pool

Abstract

The number of the fatty acid double bonds (unsaturation degree) in the plasma lipid pool was evaluated by automated ozone titration. A positive relationship between the content of double bonds, cholesterol, and glycerol was detected. The higher was plasma cholesterol level, the more double bonds contained fatty acids. At cholesterol level of 0.8–18.9 mmol/liter the double bond/cholesterol ratio approached 4.0 and double bond/glycerol ratio was 1.3–1.5. The maximum content of double bonds was detected in LDL. It was hypothesized that the greater part of plasma cholesterol is esterified with arachidonic acid possessing 4 double bonds; three fatty acids are esterified with glycerol, which altogether have 1–3 double bonds. It seems that plasma cholesterol level indirectly but significantly reflects the level of essential polyenic fatty acids, while glycerol reflects the levels of saturated and unsaturated fatty acids. The role of cholesterol in the plasma consists in the participation in transfer of essential fatty acid in the nonpolar form and their absorption by cells. LDL are the main transmitters of essential polyenic fatty acids in the form of cholesterol esters.