Labeled metabolites of hyperpolarized 1-13C pyruvate, including aspartate, malate and fumarate are detected in the rat kidney in vivo, indicating the possibility of detecting gluconeogenic flux. Pyruvate-to-bicarbonate conversion in the fasted rat liver is a marker of PEP-CK flux. Fasting resulted in lower bicarbonate and higher aspartate in the kidney. Conversely, treatment with the PEP-CK inhibitor 3-MPA did not affect bicarbonate production but did yield a lower normalized aspartate signal, with a 12-fold reduction in fasted rats. Renal pyruvate-to-bicarbonate conversion is therefore largely attributable to pyruvate hydrogenase flux, while pyruvate-to-aspartate conversion is a potential marker of renal gluconeogenesis.