A metabolomic investigation of splanchnic metabolism using 1H NMR spectroscopy of bovine blood plasma

This is the first study introducing an NMR-based metabolomic approach to elucidate metabolism in the portal-drained viscera and liver. High-resolution 1H NMR spectroscopy was performed on blood plasma obtained from the mesenteric artery, the hepatic portal vein and the hepatic vein of steers before and after interruminal infusion of short-chain fatty acids (SCFA). Partial least squares regression discriminant analysis (PLS-DA) on 1H NMR spectra obtained for arterial and portal plasma samples revealed increases in the intensities of spectral regions that could mostly be assigned to the methyl group of propionate, β-hydroxybutyrate as well as acetate in portal plasma samples compared with arterial plasma samples. PLS-DA on portal and hepatic plasma samples showed decreases in the intensities of spectral regions corresponding to the regions where methyl and methylene groups of n-butyrate, propionate, iso-butyrate, valerate, iso-valerate as well as lactate are reported to have chemical shifts. In addition, spectral differences likely to reflect a hepatic excretion of β-hydroxybutyrate and glucose were observed between portal and hepatic samples. All findings were supported by traditional biochemical analyses. Consequently, the present study clearly demonstrated the great potential of the NMR-based metabolomic approach for elucidating splanchnic metabolism. In addition, prediction of metabolite concentrations from the 1H NMR spectra obtained on plasma samples was investigated using PLS, which in relation to use 1H NMR spectra quantitatively revealed promising results with R-values in the region of 0.87-0.98.