Quantitation of metabolites in NMR spectra from isolated tissues, using 14N spectroscopy and nitrate to determine tissue volume.
Quantification of metabolites is a goal of many biomedical NMR studies. To obtain absolute measurements of metabolite concentrations is often both difficult and time-consuming. In this paper a method for determining metabolite concentrations directly is described and validated. It is applicable to studies of amphibian muscles, and with suitable precautions, to other isolated organs and tissues. The method is based upon using 14N NMR and nitrate-containing solutions to determine what fraction (F) of the sensitive volume of the RF coil is occupied by tissue. As the concentration of nitrate is known it can be used to calibrate other 14N metabolites in the tissue. Moreover, once F is determined, it can be used to calibrate metabolites in spectra from other nuclei e.g., 31P or 31C. All that is required is that a spectrum from a standard for that nucleus is obtained. Thus this method does not require any 'internal' (intrinsic to the tissue) standard, and is extremely quick and simple to use.
Wray
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Department of Physiology, University of Liverpool, London, UK.
Wilkie
D R
DR
D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D002138:Calibration; D005260:Female; D005997:Glycerylphosphorylcholine / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009132:Muscles / Q000737:chemistry; D009566:Nitrates / Q000032:analysis*; D009587:Nitrogen Isotopes; D010759:Phosphorus Isotopes; D014982:Xenopus laevis
D009566:Nitrates; D009587:Nitrogen Isotopes; D010759:Phosphorus Isotopes; D005997:Glycerylphosphorylcholine; D000255:Adenosine Triphosphate; C031618:sodium nitrate