EFFECTS OF FATTY-ACIDS AND HORMONES ON FATTY-ACID METABOLISM AND GLUCONEOGENESIS IN BOVINE HEPATOCYTES

Primary cultures of hepatocytes were used to study the effects of extr acellular oleate concentration and hormones on fatty acid metabolism a nd gluconeogenesis. Rates of oleate uptake and oxidation to acid-solub le products varied linearly as oleate concentrations increased (0.1 to 2 mM), but rates of triglyceride accumulation varied quadratically. I nsulin increased the proportion of oleate that was esterified by 22% w ithout affecting the formation of acid-soluble products. Cells incubat ed with 2 mM [1-C-14]oleate for 24 h eliminated 9.6% of the labeled in tracellular lipid as acid-soluble products in the following 24 h when no oleate was present during depletion and eliminated 7.7% when 2 mM o leate was present. Insulin reduced labeled triglyceride depletion by 4 9%. Gluconeogenesis from [2-C-14] propionate was depressed by 24%, and formation of acid-soluble products was increased by 46% in cells infi ltrated with lipid because of previous exposure to 2 mM oleate for 45 h. Rates of gluconeogenesis from propionate were reduced 23% when 2 mM oleate was present during the 3-h period that gluconeogenesis was mea sured, and the effect was not modified by lipid infiltration. Lipid in filtration influenced hepatic function, and insulin regulated hepatic triglyceride concentration.