Examination of the metabolic status of rat air pouch inflammatory exudate by high field proton NMR spectroscopy

High field proton (H-1) NMR spectroscopy was employed to investigate the metabolic status of rat air pouch inflammatory exudates obtained subsequent to the induction of inflammation with carrageenan, and the H-1 NMR profiles of these fluids were compared and contrasted with those of inflammatory human synovial fluid, rat plasma and human serum. The characteristic biochemical features obtained from H-1 NMR analysis of these exudates consisted of (1) substantially elevated levels of lactate (11.40 +/- 1.46 x 10(-3) mol dm(-3) for samples collected at a time point of 24 h post induction) with little or no NMR-detectable glucose, data consistent with a hypoxic environment and consequent anaerobic metabolism in the inflamed air pouch, and (2) high levels of the ketone body 3-D-hydroxybutyrate, providing evidence for an increased utilization of fats for energy by lymphocytes, the predominant leucocytes present in this environment. These phenomena represent a pathological extreme of the abnormal metabolic status of inflammatory human synovial fluids. (C) 1999 Elsevier Science B.V. All rights reserved.