Docosahexaenoic acid (DHA) and
eicosapentaenoic acid (EPA), known as ω-3
polyunsaturated fatty acid (PUFA), are common nutrients in daily food intake and have been shown to prevent
cardiovascular disease and improve cardiac functions.
Cardiolipin is a mitochondrial
phospholipid necessary for maintaining physiological function of mitochondria. Several studies have indicated that the
cardiolipin acyl chain compositions affect the function of
cardiolipin and mitochondria. Here, we investigated the structural changes of
cardiolipin after DHA and EPA supplementation and compared them to
arachidonic acid (AA) treatment. H9c2 cardiac myoblast was used as a cell model, and
cardiolipin species was monitored and identified via LC-MS and MS/MS. Our results showed distinct mass envelopes of
cardiolipin with the same
carbon number but different double bonds in mass spectrum. There were 116
cardiolipin species with 36 distinct mass in 6 mass envelopes identified by MS/MS. Three days of PUFA treatment resulted in decreases of low-molecular-weight
cardiolipin and increases of high-molecular-weight
cardiolipin, suggesting the incorporation of exogenous DHA, EPA and AA into mitochondrial
cardiolipin. PUFA incorporation was further verified by MS/MS analysis. More importantly, we found that DHA supplementation elevated the percent content of less unsaturated
cardiolipin species and highly unsaturated
cardiolipin species, containing ω-3 fatty acyl chains, indicating a ω-3
fatty acid incorporation mechanism with peroxidation protection. Our results indicate that PUFA supplementation differentially perturbed the fatty acyl chain compositions in the mitochondrial
cardiolipin in the H9c2 cardiac myoblast, suggesting that mitochondrial membrane and the function of mitochondria are susceptible to exogenous
lipid species.