von Morze C, Bok RA, Ohliger MA, Zhu Z, Vigneron DB, Kurhanewicz J. Hyperpolarized [(13)C]ketobutyrate, a molecular analog of pyruvate with modified specificity for LDH isoforms.
Magn Reson Med 2016;
75:1894-900. [PMID:
26059096 PMCID:
PMC4868134 DOI:
10.1002/mrm.25716]
[Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 03/11/2015] [Accepted: 03/12/2015] [Indexed: 12/25/2022]
Abstract
PURPOSE
The purpose of this study was to investigate (13) C hyperpolarization of α-ketobutyrate (αKB), an endogenous molecular analog of pyruvate, and its in vivo enzymatic conversion via lactate dehydrogenase (LDH) using localized MR spectroscopy.
METHODS
Hyperpolarized (HP) (13) C MR experiments were conducted using [(13) C]αKB with rats in vivo and with isolated LDH enzyme in vitro, along with comparative experiments using [(13) C]pyruvate. Based on differences in the kinetics of its reaction with individual LDH isoforms, HP [(13) C]αKB was investigated as a novel MR probe, with added specificity for activity of LDHB-expressed H ("heart"-type) subunits of LDH (e.g., constituents of LDH-1 isoform).
RESULTS
Comparable T1 and polarization values to pyruvate were attained (T1 = 52 s at 3 tesla [T], polarization = 10%, at C1 ). MR experiments showed rapid enzymatic conversion with substantially increased specificity. Formation of product HP [(13) C]α-hydroxybutyrate (αHB) from αKB in vivo was increased 2.7-fold in cardiac slabs relative to liver and kidney slabs. In vitro studies resulted in 5.0-fold higher product production from αKB with bovine heart LDH-1, as compared with pyruvate.
CONCLUSIONS
HP [(13) C]αKB may be a useful MR probe of cardiac metabolism and other applications where the role of H subunits of LDH is significant (e.g., renal cortex and brain).
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