Quantification of Nτ-Methylhistidine and Nπ-Methylhistidine in Chicken Plasma by Liquid Chromatography-Tandem Mass Spectrometry

The concentration of N-tau-methylhistidine in plasma provides an index of skeletal muscle protein breakdown. This study aimed to establish a quantitative method for measuring the concentrations of N-tau-methylhistidine and its isomer N-pi-methylhistidine in chicken plasma, using liquid chromatography-tandem mass spectrometry with stable isotope dilution analysis. The acceptable linear ranges of detection were 1.56-50.00 mu mol/L for N-tau-methylhistidine and 0.78-25.00 mu mol/L for N-pi-methylhistidine. The proposed method detected changes in the plasma levels of N-tau-methylhistidine and N-pi-methylhistidine in response to fasting and re-feeding. These results suggest that the method developed in this study can be used for the simultaneous measurement of N-tau-methylhistidine and N-pi-methylhistidine in chicken plasma.