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. 2006 Aug 11;2(3):499–507. doi: 10.1007/s11302-005-3980-7

Figure 2.

Figure 2

Verification of phosphate assay measured ecto-5′ nucleotidase activity. (A) Intact ARPE-19 cells produce considerably more Pi, as detected by absorbance of resorufin, when bathed with 5′AMP than 2′AMP when both nucleotides were used at 100 µM. Here and throughout the study, data are normalized to the mean absorbance value for 50AMP for each trail. Baseline represents background levels without added substrate. All compounds had no effect on the assay itself. *p < 0.05 compared to 5′AMP, 2′AMP vs. control not significant (NS), n = 4. (B) The production of Pi by intact ARPE-19 cells is completely blocked by the ecto-5′ nucleotidase inhibitor αβmADP (100 µM). Although cells from both 5′AMP and αβmADP populations were bathed in 100 µM 5′AMP, the inhibitor prevented the production of Pi. *p < 0.05 vs. 5′AMP, αβmADP vs. control NS, n = 3. (C) The alkaline phosphatase inhibitor levamisole (10 mM) had no effect on phosphate production in the presence of 100 µM 5′AMP. *p < 0.05 vs. 5′AMP, n = 12–20.