Characteristics of the rat cardiac sphingolipid pool in two mitochondrial subpopulations

Jeffrey S. Monette, Luis A. Gómez, Régis F. Moreau, Brett A. Bemer, Alan W. Taylor, Tory M. Hagen

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

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 (∼10,000pmol/mg protein) was the predominant sphingolipid regardless of mitochondrial subpopulation, and measurable amounts of ceramide (∼70pmol/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 (45pmol/mg protein). Three ceramide isotypes (C20-, C22-, and C24-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.

Original languageEnglish (US)
Pages (from-to)272-277
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume398
Issue number2
DOIs
StatePublished - Jul 2010

Keywords

  • Ceramide
  • LC-mass spectroscopy
  • Sphinganine
  • Sphingomyelin
  • Sphingosine

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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