Mechanisms by Which Saturated Triacylglycerols Elevate the Plasma Low Density Lipoprotein-Cholesterol Concentration in Hamsters Differential Effects of Fatty Acid Chain Length

These studies were designed to elucidate how shorter (MCI) and longer (HCO) chain-length saturated triacylglycerols and cholesterol interact to alter steady-state plasma LDL-choles-terol levels. When either MCT or HCO was fed in the absence of cholesterol, there was little effect on receptor-dependent LDL transport but a 3643 % increase in LDL-cholesterol pro-duction. Cholesterol feeding in the absence of triacylglycerol led to significant suppression of receptor-dependent LDL transport and a 26-31 % increase in LDL-cholesterol produc-tion. However, when the longer chain-length saturated triacyl-glycerol was fed together with cholesterol there was a marked increase in the suppression of receptor-dependent LDL trans-port and an 82 % increase in production rate. Together, these two alterations accounted for the observed eightfold increase in plasma LDL-cholesterol concentration. In contrast, feeding the shorter chain-length saturated triacylglycerol with choles-terol actually enhanced receptor-dependent LDL transport while also causing a smaller increase (52%) in the LDL-cho-lesterol production rate. As a result of these two opposing events, MCI ` feeding had essentially no net effect on plasma LDL-cholesterol levels beyond that induced by cholesterol feeding alone