• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.15 no.2
• /
• pp.59-64
• /
• 2015

Purpose: Lactate has two optical isomers, L-lactate and D-lactate. In human L-lactate is the most abundant enantiomer of lactate. As plasma and urinary levels of L-lactate is associated with inherited metabolic disorders in general, D-lactate have been linked to the presence of diabetes and inflammatory bowel disease. Previously developed techniques have shown several limitations to further evaluate D-lactate as a biomarker for this condition. In this paper, we describe a highly sensitive, specific and fast liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of D-, L-lactate in urine. Methods: D- and L-lactate were quantified using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) with labelled internal standard. Samples were derivatized with (+)-O,O'-diacety-L-tartaric anhydride (DATAN) and seperated on a Poroshell 120 EC-C18 column. Results: Quantitative analysis of D-, and L-lactate was achieved successfully. Calibration curves were linear (r>0.999) over $0.5-100{\mu}g/mL$. Stabilities for samples were within the 10% varation. Inter- and Intra-day assay variations were below 10%. Conclusion: The presented method proved to be suitable for the quantitation of D- and L-lactate and opens the possibility to explore the use of D-lactate as a biomarker.

• Journal of Nutrition and Health
• /
• v.28 no.2
• /
• pp.115-126
• /
• 1995

The effects of energy-yielding substrates on coronary circulation, myocardial oxygen metabolism, and intramyocytic adenylates of perfused Wistar control rat(WC) and spontaneously hypertensive rat(SHR) hearts were examined under basal and $\beta$-adrenergic stimulation conditions. The perfusion medium (1.0mM Ca2+) contained 5mM glucose (+5U/l insulin) in combination with 5mM pyruvate, 5mM lacate, 5mM acetate, or 5mM octanoate as energy substrates. Hearts were perfused with each substrate buffer for 20min under basal conditions. Coronary functinal hyperemia was induced by infusing for 20min isoproterenol (ISO, 1uM), a $\beta$-receptor agonist. Cardiac adenylates, glycolytic intermediates, and coronary venous lactate were measured by using an enzymatic analysis technique. Under basal conditions, acetate and octanoate significantly increased coronary flow(CF) of WC in parallel with myocardial oxygen consumption. However, CF of SHR was partly attenuated by coronary vasoconstriction despite metabolic acidosis. In addition, pyruvate and lactate depressd ISO-induced coronary functional hyperemia in SHR. It should be noted that octanoate exhibited coronary dysfunction under ISO conditions. On the other hand, fat substrates depleted myocardial high energy phosphate pool and accumulated breakdown intermediates. In SHR with coronary vasoconstriction under basal conditions, and with depressed coronary functional hyperemia, high energy phosphates were greatly depleted. These results suggest that energy substrates in the myocardium and coronary smooth muscle alter remarkably coronary circulation, and that coronary circulatory function is associated with a reserve of high energy phosphates and a balance between breakdown and nono synthesis of energy phosphates. These findings could be explained by alterations in the cytosolic redox state manipulated by LDH and hence in the cytosolic phosphorylation potential, which might be involved in hypertension of SHR.