The aim was to determine whether fed VLDL and chylomicron (CM) triacylglycerol (TAG) production rates are elevated in metabolic syndrome (MetS). Eight men with MetS (BMI 29.7 ± 1.1) and eight lean age-matched healthy men (BMI 23.1 ± 0.4) were studied using a frequent feeding protocol. After 4 h of feeding, an intravenous bolus of 2H5-glycerol was administered to label VLDL1, VLDL2, and TAG. 13C-glycerol tripalmitin was administered orally as an independent measure of CM TAG metabolism. Hepatic and intestinal lipoproteins were separated by an immunoaffinity method. In MetS, fed TAG and the increment in TAG from fasting to feeding were higher (P = 0.03 and P = 0.04, respectively) than in lean men. Fed CM, VLDL1, and VLDL2 TAG pool sizes were higher (P = 0.006, P = 0.03, and P < 0.02, respectively), and CM, VLDL1, and VLDL2 TAG production rates were higher (P < 0.002, P < 0.05, and P = 0.06, respectively) than in lean men. VLDL1, VLDL2, and CM TAG clearance rates were not different between groups. In conclusion, prandial hypertriglyceridemia in men with MetS was due to an increased production rate of both VLDL and CM TAG. Since both groups received identical meals, this suggests that in MetS the intestine is synthesizing more TAG de novo for export in CMs.

Hovorka R, Umpleby AM. A novel method for measuring intestinal and hepatic triacylglycerol kinetics. Am J Physiol Endocrinol Metab 305: E1041-E1047, 2013. First published April 16, 2013; doi:10.1152/ajpendo.00105.2013.-This study aimed to 1) develop a method that completely separated hepatic (VLDL1, VLDL2) and intestinal [chylomicron (CM)] lipoproteins and 2) use the method to measure triacylglycerol (TAG) kinetics in these lipoproteins in the fed and fasting state in healthy subjects, using intravenous [ 2 H5]glycerol as the tracer. An immunoaffinity method that completely separated hepatic and intestinal particles using sequential binding to three antibodies to apolipoprotein B-100 (apoB-100) was established and validated. Six healthy volunteers were studied in a fasted and continuous feeding study (study 1). Five additional healthy volunteers were studied in a continuous feeding study that included an oral [ 13 C3]glycerol tripalmitin tracer (study 2). In both studies, an intravenous bolus of [ 2 H5]glycerol was administered to label TAG in hepatic and intestinal lipoproteins. In both feeding studies there was sufficient incorporation of the [ 2 H5]glycerol tracer into the exogenous lipoproteins to enable isotopic enrichment to be measured. In study 2, the oral tracer enrichment in VLDL1 was Ͻ5% of CM enrichment 150 min after tracer administration, demonstrating negligible contamination of VLDL1 with apoB-48. Western blotting showed no detectable apoB-100 in CMs. VLDL1 and VLDL2 TAG fractional catabolic rate (FCR) did not differ between feeding and fasting (study 1). There was no difference between CM and VLDL1 TAG FCR in both fed studies. In fed study 2, 47% of the total TAG production rate (CM ϩ VLDL1) was from CM. This methodology may be a useful tool for understanding the abnormalities in postprandial TAG kinetics in metabolic syndrome and type 2 diabetes.very-low-density lipoprotein; chylomicron; stable isotopes; immunoaffinity; postprandial THERE IS CONSIDERABLE EVIDENCE that increased fasting plasma triacylglycerol (TAG) levels are an independent risk factor for cardiovascular disease (4) and play a role in the development of atherosclerosis (17). However, postprandial hypertriglyceridemia may be a more important risk factor for atherosclerosis than fasting hypertriglyceridemia (37), especially on a Western diet, since TAG levels are elevated for most of the day due to the frequent consumption of food (35).Hypertriglyceridemia is due to the presence of excess TAGrich lipoproteins (TRL), which consist of very low-density lipoproteins (VLDL) synthesized by the liver and chylomicrons synthesized in the small intestine in response to an intake of dietary fat. Measurement of VLDL flux using isotopic tracers has provided an invaluable insight into the abnormalities of VLDL metabolism in various diseases (3, 10). During fasting, VLDL metabolism can be measured with a fatty acid (18) or glycerol tracer to measure TAG kinetics (24) and in fasting and feeding by labeling the main protein component apolipoprotei...

PTF can inhibit the IL-6 mRNA expression and IL-6 protein secretion via nuclear factor-kappaB pathway in C2C12 skeletal muscle cells, which may be one of its mechanisms in relieving inflammation conditions and insulin resistance in C2C12 skeletal muscle cells.

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