Soler-Argilaga C, Heimberg M
J Lipid Res. 1976 Nov;17(6):605-15.
Livers from normal, fed male and female rats were perfused with different amounts of [1-14C]oleate under steady state conditions, and the rates of uptake and utilization of free fatty acid (FFA) were measured. The uptake of FFA by livers from either male or female rats was proportional to the concentration of FFA in the medium. The rate of uptake of FFA, per g of liver, by livers from female rats exceeded that of the males for the same amount of FFA infused. The incorporation by the liver of exogenous oleic acid into triglyceride, phospholipid, and oxidation products was proportional to the uptake of FFA. Livers from female rats incorporated more oleate into triglyceride (TG) and less into phospholipid (PL) and oxidation products than did livers from male animals. Livers from female rats secreted more TG than did livers from male animals when infused with equal quantities of oleate. The incorporation of endogenous fatty acid into TG of the perfusate was inhibite) by exogenous oleate. At low concentrations of perfusate FFA, however, endogenous fatty acids contributed substantially to the increased output of TG by livers from female animals. Production of 14CO2 and radioactive ketone bodies increased with increasing uptake of FFA. The partition of oleate between oxidative pathways (CO2 production and ketogenesis) was modified by the availability of the fatty acid substrate with livers from either sex. The percent incorporation of radioactivity into CO2 reached a maximum, whereas incorporation into ketone bodies continued to increase. The output of ketone bodies was dependent on the uptake of FFA, and output by livers from female animals was less than by livers from male rats. The increase in rate of ketogenesis was dependent on the influx of exogenous FFA, while ketogenesis from endogenous sources remained relatively stable. The output of glucose by the liver increased with the uptake of FFA, but no difference due to sex was observed. The output of urea by livers from male rats was unaffected by oleate, while the output of urea by livers from females decreased as the uptake of FFA increased. A major conclusion to be derived from this work is that oleate is not metabolized identically by livers from the two sexes, but rather, per gram of liver, livers from female rats take up and esterify more fatty acid to TG and oxidize less than do livers from male animals; livers from female animals synthesize and secrete more triglyceride than do livers from male animals when provided with equal quantities of free fatty acid.
在稳态条件下，用不同量的[1-14C]油酸灌注正常、喂食状态下的雄性和雌性大鼠的肝脏，并测量游离脂肪酸（FFA）的摄取和利用速率。雄性或雌性大鼠肝脏对FFA的摄取与培养基中FFA的浓度成正比。对于相同量的注入FFA，雌性大鼠肝脏每克肝脏对FFA的摄取速率超过雄性大鼠。肝脏将外源性油酸掺入甘油三酯、磷脂和氧化产物的量与FFA的摄取量成正比。与雄性动物的肝脏相比，雌性大鼠的肝脏将更多的油酸掺入甘油三酯（TG），而掺入磷脂（PL）和氧化产物的量较少。当注入等量的油酸时，雌性大鼠的肝脏比雄性大鼠的肝脏分泌更多的TG。外源性油酸抑制灌注液中内源性脂肪酸掺入TG。然而，在低浓度的灌注液FFA条件下，内源性脂肪酸对雌性动物肝脏TG输出增加有很大贡献。14CO2和放射性酮体的产生随着FFA摄取的增加而增加。两性肝脏中脂肪酸底物的可用性改变了油酸在氧化途径（CO2产生和生酮作用）之间的分配。放射性物质掺入CO2的百分比达到最大值，而掺入酮体的量继续增加。酮体的输出取决于FFA的摄取，雌性动物肝脏的输出低于雄性大鼠肝脏。生酮速率的增加取决于外源性FFA的流入，而内源性来源的生酮作用保持相对稳定。肝脏葡萄糖的输出随着FFA的摄取而增加，但未观察到性别差异。雄性大鼠肝脏尿素的输出不受油酸影响，而雌性大鼠肝脏尿素的输出随着FFA摄取的增加而减少。这项工作得出的一个主要结论是，两性肝脏对油酸的代谢并不相同，而是每克肝脏，雌性大鼠的肝脏比雄性动物的肝脏摄取和酯化更多的脂肪酸到TG中，氧化更少；当提供等量的游离脂肪酸时，雌性动物的肝脏比雄性动物的肝脏合成和分泌更多的甘油三酯。
