LIPID-COMPOSITION OF HDL SUBFRACTIONS IN DOG PLASMA AND LYMPH

We report the lipid composition of dog plasma and peripheral lymph lip oproteins as separated into pre-beta, alpha, and pre-alpha fractions b y agarose gel electrophoresis. Plasma lipoproteins with alpha mobility have a composition different from that of plasma lipoproteins with pr e-alpha mobility, having 9% versus 11% free cholesterol, 21% versus 17 % cholesterol ester, 1% versus 16% triacylglycerol, and 69% versus 56% phospholipid. On the other hand, lymph alpha and pre-alpha lipoprotei ns have compositions that are quite similar (9% versus 7% free cholest erol, 17% versus 17% cholesterol ester, 2% versus 4% triacylglycerol, and 71% versus 71% phospholipid). The lipid compositions of plasma and lymph alpha lipoproteins are guile similar (9% versus 9% free cholest erol, 21% versus 17% cholesterol ester, 1% versus 2% triacylglycerol, and 70% versus 72% phospholipid). The lipid compositions of plasma and lymph pre-alpha lipoproteins are different (11% versus 7% free choles terol, 17% versus 17% cholesterol ester, 16% versus 4% triacylglycerol , and 56% versus 71% phospholipid). Peripheral lymph lipoproteins with pre-beta mobility contained 15% cholesterol, 13% cholesterol ester, 1 0% triacylglycerol, and 61% phospholipid. Compared with plasma, periph eral lymph lipoproteins are free cholesterol-enriched in all fractions . Calculated stoichiometric ratios of lipid to apoA-I indicate that pr e-beta lipoproteins contain one molecule of apoA-I per particle, alpha lipoproteins have two molecules of apoA-I per particle, and pre-alpha lipoproteins have four molecules of apoA-I per particle.