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Brain high‐energy phosphates and creatine kinase synthesis rate under graded isoflurane anesthesia: An in vivo 31 P magnetization transfer study at 11.7 tesla
Author(s) -
Bresnen Andrew,
Duong Timothy Q.
Publication year - 2015
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25136
Subject(s) - phosphocreatine , isoflurane , creatine kinase , creatine , in vivo , chemistry , magnetization transfer , adenosine triphosphate , nuclear magnetic resonance , endocrinology , biochemistry , medicine , biology , magnetic resonance imaging , energy metabolism , physics , microbiology and biotechnology , organic chemistry , radiology
Purpose The creatine kinase rate of metabolic adenosine triphosphate (ATP) synthesis is an important metabolic parameter but is challenging to measure in vivo due to limited signal‐to‐noise ratio and long measurement time. Theory and Methods This study reports the implementation of an accelerated 31 P Four Angle Saturation Transfer (FAST) method to measure the forward creatine kinase (CK) rate of ATP synthesis. Along with a high‐field scanner (11.7 Tesla) and a small sensitive surface coil, the forward CK rate in the rat brain was measured in ∼5 min. Results Under 1.2% isoflurane, the forward CK rate constant and metabolic flux were, respectively, k f , CK = 0.26 ± 0.02 s −1 and F f,CK = 70.8 ± 4.6 μmol/g/min. As a demonstration of utility and sensitivity, measurements were made under graded isoflurane. Under 2.0% isoflurane, k f , CK = 0.16 ± 0.02 s −1 and F f,CK = 41.0 ± 4.2 μmol/g/min, corresponding to a 38% and 42% reduction, respectively, relative to 1.2% isoflurane. By contrast, the ATP and phosphocreatine concentrations were unaltered. Conclusion This study demonstrated the 31 P FAST measurement of creatine kinase rate of ATP synthesis in rat brain with reasonable temporal resolution. Different isoflurane levels commonly used in animal models significantly alter the CK reaction rate but not ATP and phosphocreatine concentrations. Magn Reson Med 73:726–730, 2015. © 2014 Wiley Periodicals, Inc.