Figure 2.

HP [1-¹³C]pyruvate metabolism of renal tissue slices. Schematic illustrating the metabolism of HP [1-¹³C]pyruvate to [1-¹³C] lactate and [1-¹³C] alanine, catalyzed by LDH and alanine aminotransaminase (ALT), respectively (A). ¹³C pyruvate is transported intracellularly via MCT1, and ¹³C lactate is exported out of the cells via MCT4. Representative hyperpolarized ¹³C spectrum of grade 2 ccRCC tissue slices (B). Inset shows the lactate kinetics over 5 minutes. Bar graphs of normalized HP [1-¹³C] lactate and [1-¹³C] alanine to the injected pyruvate in the tissue slices (C). Benign renal tumors and ccRCCs show 2.7- and 1.7-fold higher HP ¹³C lactate levels, consistent with increased aerobic glycolysis compared with normal renal parenchymal tissues. The observed ¹³C lactate level is 59% lower in ccRCCs than in benign renal tumors. White bars indicate normal renal tissue, gray bars indicate benign renal tumors, and black bars indicate ccRCC, with standard deviation error bars.