Table 2. Mass isotopomer distribution in lactate from incubation medium.

Hepatocytes were incubated as in Table 1. m0, m1, m2 and m3 were calculated as described in the Experimental section. The ratio m2(lactate)×2/M2(glycogen) reflects the contribution of G6P to lactate. One minus this ratio should be the contribution of pyruvate from alanine or Krebs cycle, or other contributions such as glycerol to the triose phosphate pool. Means±S.E.M. of several experiments (n=6) are provided.

	m0	m1	m2	m3	Σmn	m2(lactate)×2/M2(glycogen)
Glucose	0.850±0.006	0.029±0.001	0.118±0.006	0.003±0.0012	0.275±0.012	0.641±0.026
Glucose+,glutamine	0.929±0.004	0.006±0.001	0.065±0.003	−0.001±0.0010	0.135±0.006	0.345±0.014
Glucose+,lactate/pyruvate (9:1)	0.982±0.004	0.002±0.001	0.009±0.001	0.006±0.0028	0.039±0.010	0.059±0.008
Glucose+,fructose	0.917±0.006	0.015±0.001	0.067±0.005	0.001±0.0001	0.152±0.011	0.410±0.027