Fig. 3.

All ¹³C labeled glucose isotopomers (including the [U-¹³C]-d-glucose tracer) in plasma. Positional glucose ¹³C isotopomer fractions as per cent of the total ¹³C enriched fraction in plasma (Y axis, Σm_{n=C1,2,3,4,5,6}) at 0, 60, 120 and 180 min (X axis) after tracer load. The various isotopomers indicate: M1, pyruvate carboxylase activity; M2, pyruvate dehydrogenase activity and complete TCA cycle turnaround; M3, glucose generated from [U-¹³C₃]-dl-lactate and the Cori cycle; M4, non-oxidative pentose cycle; and M5, oxidative pentose cycle (mean; n = 8) (Lee et al. 1991)