Table 2

GAA and Cr synthesis experiments in rat cerebellar granule cells

Concentration of [15N2]Arg and [13C2,15N]Gly in the medium (mmo1/L)

[15N2]Arg in the cells

(nmol/mg protein)

Arg in the cells

(nmol/mg protein)

[15N2]Arg/Arg


0

1.6 ± 0.8

153.4 ± 105.3

0.009 ± 0.001

10

56.3 ± 20.4 NS

55.3 ± 6.5

1.00 ± 0.25


[13C2,15N]Gly in the cells

(nmol/mg protein)

Gly in the cells

(nmol/mg protein)

13C2,15N]Gly/Gly


0

1.8 ± 1.2

470.8 ± 232.7

0.007 ± 0.004

10

710.5 ± 216.1 **

137.9 ± 29.8

5.08 ± 0.68


[13C215N3]GAA in the cells(nmol/mg protein)

GAA in the cells

(nmol/mg protein)

[13C215N3]GAA/GAA


0

0.12 ± 0.07

2.08 ± 1.43

0.085 ± 0.029

10

7.4 ± 3.2 *

0.22 ± 0.05

33.3 ± 7.9


[13C215N3]Cr in the cells

(nmol/mg protein)

Cr in the cells

(nmol/mg protein)

[13C215N3]Cr/Cr


0

0.04 ± 0.02

261.3 ± 138.4

< 0.001

10

1.6 ± 0.4**

62.2 ± 15.3

0.027 ± 0.007


Intracellular concentrations of Gly, [13C2,15N]Gly, Arg, [15N2]Arg, GAA, [1,2-13C2,15N3]GAA, Cr, and [1,2-13C2,15N3]Cr after 24 hours in vitro incubation with 10 mmol/L [15N2]Arg and 10 mmol/L [13C2,15N]Gly. Zero concentration in the first column (first line) corresponds to cells incubated in medium without labeled precursors. The value reported of labeled compounds is due to background noise. The statistical significance of the differences between intracellular concentrations of labeled and unlabeled compounds was assessed by paired Student's t-test: NS not significant, * p < 0.05, ** p < 0.01. The intracellular concentration of [13C2,15N]Gly was significantly higher than that of Gly and the concentration of [15N2]Arg was similar to that of Arg. Accordingly, the intracellular [13C215N3]GAA concentration was significantly higher than GAA concentration whereas [13C215N3]Cr is significantly lower than Cr. The ratios express the relative intracellular availability of labeled and unlabeled forms (right column).

Carducci et al. BMC Neuroscience 2012 13:41   doi:10.1186/1471-2202-13-41

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