[Preprint]. 2023 Apr 13:2023.04.12.536558. [Version 1] doi: 10.1101/2023.04.12.536558

Table 3.

Flux ratios and absolute rates measured in mice infused with [3-13C] lactate. APE indicates the atom percent enrichment, and GNG denotes gluconeogenesis.

Equation

Interpretation

T u r n o v e r = (\frac{T r a c e r A P E}{P l a s m a A P E} - 1) * I n f u s i o n r a t e

Whole-body endogenous glucose production (EGP) or palmitate turnover

L i v e r g l y c o g e n o l y s i s = \frac{{[L i v e r g l y c o g e n]}_{t - 2} - {[G l y c o g e n]}_{t}}{t}

Liver glycogenolysis rate

T o t a l g l u c o n e o g e n e s i s = E G P - l i v e r g l y c o g e n o l y s i s

Whole-body gluconeogenesis (V_GNG)

\frac{V_{P E P C K}}{V_{G N G}} ~ \frac{V_{P C}}{V_{G N G}} = \frac{{[^{13} C_{2}]}_{g l u c o s e}}{X F E^{2}}

Fraction of gluconeogenesis derived from pyruvate, measured in plasma (i.e. whole-body), liver, or kidney

X F E = \frac{1}{1 + \frac{[^{13} C_{1}] g l u c o s e}{2 * [^{13} C_{2}] g l u c o s e}}

Fractional triose enrichment

C o r r e c t e d [^{13} C_{2}] g l u c o s e = M e a s u r e d [^{13} C_{2}] g l u c o s e - 2 * [C 4 C 5 C 6 -^{13} C_{2}] g l u c o s e

Doubly-labeled glucose arising from the condensation of two singly labeled trioses, correcting for doubly labeled glucose arising from one doubly labeled triose condensing with an unlabeled triose

\frac{G N G_{K}}{G N G} = 1 - \frac{G N G f r o m p y r u v a t e_{T} - G N G f r o m p y r u v a t e_{K}}{G N G f r o m p y r u v a t e_{L} - G N G f r o m p y r u v a t e_{K}}

Fractional contribution of the kidney to total gluconeogenesis

G N G_{K} = \frac{G N G_{K}}{G N G} * V_{G N G}

Absolute rate of gluconeogenesis from the kidney