J Lipid Res
-
Free fatty acids (FFA) released during the lipolysis of triglyceride (TG)-rich lipoproteins in vivo are generally believed to be bound to serum albumin. When hypertriglyceridemic (HTG) sera were lipolyzed in vitro by purified bovine milk lipoprotein lipase (LpL), there was an 11- to 18-fold increase in serum FFA levels, and a major portion (> 80%) of the FFA in serum was partitioned to lipoprotein fractions. The greatest portion (33%) of FFA in lipolyzed HTG serum was associated with newly formed flocculent remnants that banded just below low density lipoproteins (LDL) in the density gradient tube. ⋯ The cytotoxic potencies of FFA bound to lipoproteins and albumin were further compared after in vitro incorporation of FFA (oleic acids) into LDL and to albumin. FFA bound to LDL but not to albumin were cytotoxic to cultured MPM; the cytotoxicity of FFA bound to LDL was more closely related to the FFA to LDL-cholesterol molar ratio than to the total FFA concentration in the culture dish. The ability of FFA bound to LDL and albumin to induce foam cell formation was studied in THP-1 monocyte-derived macrophages, which were less susceptible to cytotoxicity produced by FFA bound to LDL than MPM.(ABSTRACT TRUNCATED AT 400 WORDS)