Hepatic zonation of carbon and nitrogen fluxes derived from glutamine and ammonia transformations

Table 1 Changes in glucose,¹⁴CO₂ and urea productions and oxygen uptake due to glutamine + ammonia as a function of the arterial ammonia infusion in antegrade and retrograde perfusion.

Metabolic parameter	Ammonia infusion (μmol min⁽¹ g⁽¹)	J_ant(μmol min⁽¹ ml⁽¹)	J_ret(μmol min⁽¹ ml⁽¹)	p
Extra glucose production	1.25 4.6 9.2	0.052 ± 0.004 (n = 4) 0.101 ± 0.011 (n = 4) 0.165 ± 0.018 (n = 5)	0.137 ± 0.022 (n = 4) 0.251 ± 0.036 (n = 4) 0.303 ± 0.040 (n = 4)	0.002 0.007 0.011
Extra lactate production	1.25 4.6 9.2	0.038 ± 0.006 (n = 4) 0.045 ± 0.010 (n = 4) 0.055 ± 0.008 (n = 5)	0.048 ± 0.014 (n = 5) 0.112 ± 0.023 (n = 5) 0.086 ± 0.008 (n = 5)	0.57 0.045 0.025
Extra oxygen uptake	1.25 4.6 9.2	0.284 ± 0.045 (n = 4) 0.524 ± 0.040 (n = 4) 0.815 ± 0.076 (n = 5)	0.451 ± 0.069 (n = 5) 0.877 ± 0.136 (n = 4) 1.090 ± 0.070 (n = 5)	0.098 0.047 0.029
¹⁴CO₂ production	1.25 4.6 9.2	0.182 ± 0.037 (n = 3) 0.318 ± 0.028 (n = 4) 0.545 ± 0.046 (n = 5)	0.425 ± 0.067 (n = 5) 0.611 ± 0.040 (n = 5) 0.886 ± 0.058 (n = 5)	0.041 0.001 0.002
Extra urea production	1.25 4.6 9.2	0.496 ± 0.046 (n = 4) 0.702 ± 0.028 (n = 3) 0.970 ± 0.078 (n = 5)	0.421 ± 0.067 (n = 5) 0.663 ± 0.056 (n = 4) 1.117 ± 0.059 (n = 5)	0.41 0.67 0.17

The raw data were obtained from experiments of the type illustrated by Figures 3 and 4. The glutamine concentration was the same for all experiments, namely 0.6 mM. The changes correspond to the final metabolic fluxes in the presence of both glutamine and ammonia (70 minutes perfusion time in Figures 3 and 4), subtracted from the fluxes in the sole presence of glutamine. All values were expressed as μmol per minute per ml cell space that is accessible via the hepatic artery in each perfusion mode. The data were analyzed by variance analysis. The p values were obtained by applying the Student-Newman-Keuls test.

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