OLEIC ACID-RICH FATS INCREASE THE CAPACITY OF POSTPRANDIAL SERUM TO PROMOTE CHOLESTEROL EFFLUX FROM FU5AH CELLS

Cell cholesterol efflux to serum is stimulated after an oral fat load. The impact of meal fatty acid composition was explored by measure of serum promoted cholesterol efflux from Fu5AH cells after ingestion of 4 different fats: sunflower (Sf), oleic-sunflower (O1), a mixed oil (M x), and beef tallow (Bt). High density lipoprotein (HDL)(2) and HDL(3) were isolated and analyzed. Cholesterol efflux increased regularly af ter O1 (P < 0.05 at 4 h and P < 0.02 at 8 h), and 8 h after Mx (P < 0. 02) or Bt (P < 0.05), but not after Sf. Percent HDL, phospholipids inc reased after O1 (P < 0.05 at 6 h and P < 0.01 at 8 h) and 8 h after Mx (P < 0.01). After O1, variations in efflux and percent phospholipids in HDL(3) (but not HDL(2)) were positively correlated (r = 0.929; P = 0.007 at 6 h). Using HDL(3), efflux increased 6 h after O1 (P < 0.05) but not after Sf, and efflux was correlated with HDL(3) phospholipid c oncentration in medium (r = 0.913; P = 0.011). Thus postprandial incre ase in cholesterol efflux is influenced by ingested fats in relation t o increased phospholipid availability on HDL(3). The protective effect of monounsaturated fatty acids against atherogenesis might be partly mediated by an enhanced ability of postprandial serum to accept cell c holesterol.