Study on Tissue Distribution of A Variety of Endogenous Metabolites by Air Flow Assisted Ionization-Ultra High Resolution Mass Spectrometry Imaging / 分析化学

ABSTRACT

As a promising new molecular imaging technique,mass spectrometry imaging(MSI) has attracted more and more attention in the field of biomedicine. A method of air flow assisted ionization-ultra high resolution mass spectrometry-based mass spectrometric imaging (AFAI-MSI) was developed to profile endogenous metabolites in rat kidney tissue in this study. Rat kidneys were collected and cut into frozen tissue sections,and then were analyzed on an AFAI-MSI system in positive ion mode using acetonitrile-isopmpyl alcohol-water (442,V/V,5 μL/min) as spray solvent,N2as spray gas(0.6 MPa) and air as assisting gas (45 L/min). The mass range and resolution were set to be 70-1000 Da and 70000, respectively. As a result,a total of 38 metabolites, including organic amines, sugars, vitamins, peptides, neurotransmitters, organic acids,phospholipids,sphingolipids,glyceride,and cholesterol esters, were identified and imaged to characterize their tissue-specific distribution in kidney tissues, and some metabolites, such as choline, acetylcoline,betaine,phoshocholine,and glycerophosphocholine were found to have distinct distribution along the cortex-medulla axis,which may be involved in the formation of osmotic pressure gradient in the kidney. The proposed ultra high resolution mass spectrometry based AFAI-MSI method could work without sample pretreatment, showed high sensitivity and wide metabolite coverage, and was expected to provide a new analytical approach for the research of in situ characterization and metabolic regulation mechanism of endogenous metabolites in kidney.