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Kinetics of PME/Pi in pig kidneys during cold ischemia
Author(s) -
von Elverfeldt Dominik,
Niekisch Miriam,
Quaschning Thomas,
Saman Andre El,
Kirste Günter,
KrämerGuth Annette,
Hennig Jürgen
Publication year - 2007
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1120
Subject(s) - phosphomonoesters , chemistry , transplantation , pi , kinetics , metabolite , nuclear magnetic resonance , ischemia , kidney , nuclear medicine , biochemistry , medicine , inorganic phosphate , phosphate , physics , quantum mechanics
Quality assessment of renal grafts via 31 P magnetic resonance spectroscopy (MRS) has been investigated since 1986. As ATP concentrations decay rapidly during cold ischemia, the ratio of phosphomonoesters (PME) to inorganic phosphate (Pi O ) within the organ (PME/Pi O ) is commonly used as a quality marker and is considered to be the most reliable parameter. MRS did not lead to any delay in the transplantation procedure since it was performed during the time necessary for immunological matching (cross‐match). Differences in the time period until transplantation call for extrapolation of the measured ratio to the end of cold ischemia before correlating with graft performance after transplantation. Therefore, quantitative determination of PME/Pi O kinetics is essential. As a model for metabolite decay in human renal grafts, pig kidneys obtained from a slaughterhouse were monitored for up to 80 h via 31 P MRS at 2 T. By employing chemical shift imaging (CSI) with a spatial resolution of approximately 1 × 1 × 4 cm 3 , it was possible to reduce partial volume effects significantly. The improved spectral resolution gained through CSI enabled reliable PME/Pi O ratios to be determined only from those voxels containing renal tissue. Spectra were fitted automatically using the magnetic resonance user interface (MRUI), with prior knowledge obtained from unlocalized spectra when necessary. A monoexponential time dependence of PME/Pi O for histidine–tryptophane–alpha‐ketoglutarate (HTK)‐perfused kidneys during cold ischemia was observed, and the determined value of the decay constant α was 0.0099 ± 0.0012 h −1 . In University of Wisconsin solution (UW)‐perfused kidneys, an α of 0.0183 ± 0.0053 h −1 was determined. Determination of the decay constant enables a usable extrapolation of PME/Pi O for quality assessment of UW perfusion and a reliable extrapolation for HTK‐perfused human renal grafts. Copyright © 2007 John Wiley & Sons, Ltd.