Journal
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Volume 398, Issue 2, Pages 272-277Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.bbrc.2010.06.077
Keywords
Ceramide; Sphingomyelin; Sphingosine; Sphinganine; LC-mass spectroscopy
Categories
Funding
- National Institute on Aging [2R01AG017141]
- Direct For Education and Human Resources
- Division Of Graduate Education [0965820] Funding Source: National Science Foundation
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Mitochondrial sphingolipids play a diverse role in normal cardiac function and diseases, yet a precise quantification of cardiac mitochondrial sphingolipids has never been performed. Therefore, rat heart interfibrillary mitochondria (IFM) and subsarcolemmal mitochondria (SSM) were isolated, lipids extracted, and sphingolipids quantified by LC-tandem mass spectrometry. Results showed that sphingomyelin (similar to 10,000 pmol/mg protein) was the predominant sphingolipid regardless of mitochondrial subpopulation, and measurable amounts of ceramide (similar to 70 pmol/mg protein) sphingosine, and sphinganine were also found in IFM and SSM. Both mitochondrial populations contained similar quantities of sphingolipids except for ceramide which was much higher in SSM. Analysis of sphingolipid isoforms revealed ten different sphingomyelins and six ceramides that differed from 16- to 24-carbon units in their acyl side chains. Sub-fractionation experiments further showed that sphingolipids are a constituent part of the inner mitochondrial membrane. Furthermore, inner membrane ceramide levels were 32% lower versus whole mitochondria (45 pmol/mg protein). Three ceramide isotypes (C-20-, C-22-, and C-24-ceramide) accounted for the lower amounts. The concentrations of the ceramides present in the inner membranes of SSM and IFM differed greatly. Overall, mitochondrial sphingolipid content reflected levels seen in cardiac tissue, but the specific ceramide distribution distinguished IFM and SSM from each other. (C) 2010 Elsevier Inc. All rights reserved.
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