Structural studies of NMR detected lipids in myocardial ischemia

Lipid-induced abnormalities in myocardial function have been implicated in a number of ischemic events including the accumulation of lipids in human myocardium following myocardial infarction. Although animal models have shown the source of these lipids to be triglycerides, the specific species involved has not been identified. In order to better understand the mechanism(s) defining this lipid accumulation, it follows that the identification of the lipids involved may be important in achieving this aim. Therefore, this study examined the use of NMR probes for delineating the biochemical makeup of the increased 1H NMR observed lipid signal following myocardial infarction. Specifically, the present study demonstrated the utility of the spin-echo pulse sequence for the study of alterations in myocardial lipids following ischemic injury. Spin-echo spectra allowed the analysis of subsets of lipids within the large lipid pool inherent in most myocardium. The analyses of the chemical shifts of the lipid resonances provided a simple yet powerful means for deducing lipid class associated with the ischemic injury and suggested the species arises predominantly from saturated lipids. The examination of the CH2/CH3 NMR ratio provided additional information regarding the species involved, however, because the spin-echo technique was utilized, which may distort certain signal intensities, caution must be exercised in interpreting the specific species involved. With this in mind, a tentative assignment has been given to octanoic acid. Finally, a temperature dependence of the lipid signals was noted and determined to be unique for spin-echo lipid.(ABSTRACT TRUNCATED AT 250 WORDS)