Competitive effects of long-chain-triglyceride emulsion on the metabolism of medium-chain-triglyceride emulsions

Abstract

This study was conducted to assess the potential metabolic competitive interactions of intravenous medium-chain-triglyceride (MCT) and long-chain-triglyceride (LCT) lipid emulsions. To assess this competition increasing concentrations of LCT emulsion were added to an intravenous dose of MCT emulsion of 3.0 g/kg body wt up to a maximum dose of 3.0 g LCTs/kg body wt. Blood samples were assessed for competitive interactions by analyzing the following metabolites: glucose, insulin, lactate, pyruvate, ketones (acetoacetate, beta-hydroxybutyrate), elimination of triglycerides, and free fatty acids. Evaluation of the data showed a strong competitive interaction between the MCT and LCT emulsions. This competition was evident as soon as LCTs were added to the MCT infusions and appeared to favor LCTs for removal and metabolism over MCTs. This appears to indicate that there is a peripheral, strong affinity site for LCT removal and metabolism and a shared peripheral site and specific visceral site for MCT removal and metabolism.

Lipid Resuscitation of Bupivacaine Toxicity

“…1 An alternative mechanism is the "lipid flux" theory, whereby lipid emulsions supply the mitochondria with sufficient substrate to enable energy production, which counters the impaired fatty acid delivery caused by local anesthetics. 13 Furthermore, there are reports of differences in speed of hydrolysis and oxidation, 14 the binding affinity of bupivacaine, 15 the production of ketone bodies, 16 and metabolic pathways of transport and utilization 17 between LCT and LCT/MCT emulsions. Some authors also believe that they may have different effects on bupivacaine-induced cardiotoxicity because of their different particle sizes (430 nm vs. 280 nm, respectively).…”

Repression of Fat-Dependent Intestinal Apo A-IV mRNA Abundance by Medium Chain Triacylglycerols and Proteins, and Elevation by Carbohydrates of Fat-Dependent Apo A-IV Transport in Suckling Rat Pups.

“…In contrast, administration of MCT with soybean oil did not result in an elevation of serum triacylglycerols, as compared to administration of soybean oil alone, although MCT administration increased the accumulation of intestinal triacylglycerols. Thus, MCT inhibited LCT transport, possibly by enhancing LCT oxidation in the intestine (21). A challenge with trilaurin did not affect soybean oil-dependent elevation of apo A-IV mRNA and serum apo A-IV concentration.…”

“…In suckling rats, MCT provides 70-80% of the substrate for ketogenesis (8), and formation of ketone bodies from LCT is also greater due to larger quantities of carnitine and the activity of carnitine palmitoyltransferase in suckling rats (26), as compared to that in adult rats (27) . In addition, it has been reported that administration of MCT results in a concomitant increase of LCT derived ketone body formation in rats (21). Therefore it is considered that ingestion of MCT decreased the amount of apo A-IV mRNA, possibly through a metabolic event which drives intestinal fatty acids into oxidative utilization rather than into an esterification process.…”

Effect of medium‐chain fatty acid positional distribution in dietary triacylglycerol on lymphatic lipid transport and chylomicron composition in rats

“…The position of longer-chain saturated fatty acids in a triacylglycerol molecule greatly influences related intestinal absorption and consequently modifies absorption rates of other longer-chain fatty acids (13)(14)(15)(16)(17)(18)(19). The importance of the position of MCF in a triacylglycerol molecule has also been advocated by us (5) and others (6,7,(9)(10)(11)(12)20,21). Occasionally, lymphatic transport of dietary fats in rats has been measured by infusing fat-emulsion into the stomach or duodenum (22).…”

“…Synthetic fats containing MCF are now used in various fields to improve the physiological properties of MCF (3)(4)(5)(6)(7)(8)(9)(10)(11). Absorption of MCF seems to be better than longer-chain fatty acids, but little attention has been directed to the interactive effects of MCF on longer-chain fatty acids with regard to absorption of synthetic fats and dietary fats (6,7,12). The position of longer-chain saturated fatty acids in a triacylglycerol molecule greatly influences related intestinal absorption and consequently modifies absorption rates of other longer-chain fatty acids (13)(14)(15)(16)(17)(18)(19).…”