Table 3.

Maintenance by nucleosides of a high ATP level in glucose-deprived cultured astrocytes

Substrate	Control		Dipyridamole
	LDH (%)	ATP content (nmol/mg)	LDH (%)	ATP content (nmol/mg)	ATP content (% of control)
None	11 ± 4	8 ± 2***	10 ± 5	8 ± 2***	100 ± 0
Glucose	12 ± 8	28 ± 3	5 ± 6	29 ± 5	104 ± 18
AMP	9 ± 13	30 ± 6	7 ± 5	17 ± 5**, #	57 ± 17**
ADP	15 ± 5	23 ± 3	17 ± 11	8 ± 1***, ##	35 ± 4***
Adenosine	7 ± 5	38 ± 5	2 ± 3	21 ± 3##	55 ± 8***
Inosine	8 ± 5	32 ± 4	5 ± 5	14 ± 1**, ##	44 ± 3***
Guanosine	8 ± 8	27 ± 5	17 ± 13	10 ± 1***, #	37 ± 4***

The cultures were incubated for 24 h in glucose-free incubation buffer that had been supplemented with 2 mM of the indicated substrates in the absence or the presence of 10 µM dipyridamole before the cellular ATP content and the extracellular LDH activity (in percent of the initial cellular LDH activity) were determined. The initial cellular ATP content at the onset of the incubation was 34.7 ± 3.9 nmol/mg, the initial cellular LDH activity 173 ± 58 nmol/(min × well) and the initial protein content 116 ± 42 µg/well. The data represent means ± SD of values that were obtained in experiments performed on 3 independently prepared cultures. The significance of differences (ANOVA with Bonferroni post hoc test) compared with the data obtained for glucose-treated cells is indicated by**p < 0.01 and ***p < 0.001. The significance of differences (t-test) between values observed for cells that had been treated with and without dipyridamole is indicated by ^#p < 0.05 and ^##p < 0.01