An LC-MS/MS method to quantify acylcarnitine species including isomeric and odd-numbered forms in plasma and tissues

Abstract

transport of activated fatty acids (acyl-CoAs) from the cytosol across the inner mitochondrial membrane into the matrix where fatty acid oxidation takes place. It has now become clear that a net effl ux of acylcarnitine species from the mitochondria into the cytosol and ultimately into plasma is particularly important in situations of impaired fatty acid oxidation to prevent accumulation of potentially toxic acyl-CoA intermediates in the mitochondrion ( 2, 3 ). How acylcarnitines are released into the extracellular space is not known, but changes in plasma and/or urinary acylcarnitine profi les are used to detect disorders in fatty acid and amino acid oxidation ( 4 ). More recently, alterations in plasma acylcarnitine profi les were described as strongly associated with obesity and type 2 diabetes ( 5-7 ). A broad spectrum of short-, medium-, and long-chain acylcarnitine species is generated from multiple metabolic routes including various fatty acid and amino acid oxidation pathways. A comprehensive quantifi cation that covers as many as possible of these entities is therefore not only important for proper clinical diagnosis of inherited enzymatic impairments, but also for basic studies of complex diseases such as the metabolic syndrome.Acylcarnitine profiles are commonly established by direct infusion ESI-MS/MS. This technology, however, does not allow the discrimination of isomeric acylcarnitine species. Furthermore, isobaric matrix interferences can lead to an overestimation of metabolite concentrations producing false positive results, in particular, for compounds with low abundance ( 8 ). Although LC-MS/ MS methods have been developed for successful separation of isomeric compounds ( 9-12 ), the identifi cation of the exact compound in the chromatogram often remains Acylcarnitines are intermediates in fatty acid and amino acid breakdown generated from the conversion of acylCoA species by the action of carnitine acyltransferases ( 1 ). The formation of carnitine conjugates is crucial for the

GPAT Gene Silencing in Muscle Reduces Diacylglycerols Content and Improves Insulin Action in Diet-Induced Insulin Resistance

“…Acyl-carnitine concentration was measured according to Giesbertz [ 43 ] with a small modification. In short, skeletal muscle samples were pulverized and then extracted with the use of ice-cold methanol and centrifuged at 10,000 g , 4 °C, for 10 min.…”

Differential mobility spectrometry (DMS) reveals the elevation of urinary acetylcarnitine in non‐human primates (NHPs) exposed to radiation

“…5 Historically, acylcarnitines have been measured by gas chromatography-mass spectrometry (GC-MS), 6 or liquid chromatography-tandem mass spectrometry (LC-MS/MS). [7][8][9] However, GC-MS requires chemical modification steps, and both GC-MS and LC-MS/MS typically require significant amounts of time for chromatography. Consequently, a simpler analytical technique is desirable for high-throughput acylcarnitine analysis.…”

Specificity, Dose Dependency, and Kinetics of Markers of Chicken and Beef Intake Using Targeted Quantitative LC‐MS/MS: A Human Intervention Trial

“…Quantitative analysis of amino acid and acylcarnitine concentrations was performed using LC-MS/MS based on the methods described earlier. [20,21] A complete list of all analytes in the measurement, including HPLC retention times, mass transitions, and MS settings, can be found in Table S1, Supporting information. Calibration data, accuracies, and precisions are found in Tables S2-S4, Supporting information, respectively.…”