SIMULTANEOUS MEASUREMENT OF BOTH LIPID AND LACTATE IN ISOLATED RAT HEARTS BY H-1-NMR SPECTROSCOPY

Myocardial lipid and lactate levels are sensitive indicators of bioche mical status: lipid levels have been shown to increase in response to high fat diets, disease or metabolic stress and elevated lactate level s are indicative of reduced oxygen supply. Selective measurement of la ctate or lipid levels by H-1 NMR is not straightforward since both the lactate methyl group and lipid methylene groups resonate at 1.3 ppm. We have overcome this difficulty by employing spectral editing techniq ues to observe both lipid methylene and lactate methyl resonances, and have measured lipid and lactate levels in perfused rat hearts during control perfusion and in response to metabolic stress. Lactate increas ed during ischemia and decreased during reperfusion, and the ischemia- induced increase is inhibited by iodoacetate, as expected. In contrast , lipid levels increased during ischemia and remained elevated during reperfusion. Hearts from rats fed high fat diet show elevated lipid le vels during control perfusion. Data obtained by H-1 NMR are consistent with biochemical data, validating the technique.