Inhibition of purified chicken gizzard smooth muscle ecto-ATPAse by P2 purinoceptor antagonists.

Several "specific" inhibitors of P2 purinergic receptors (purinoceptors) were evaluated for their ability to inhibit purified chicken gizzard cell membrane ecto-ATPase. The P2 purinoceptor antagonists tested included suramin, triazine based reactive textile dyes, and non-specific total protein dyes. All inhibited the purified ecto-ATPase, with half maximal inhibition from approximately 20 to 120 microM. Thin layer chromatography purified Cibacron Blue 3GA, also known as Reactive Blue 2, was demonstrated to inhibit immunopure ecto-ATPase with an IC50 of 44 microM. Thus, for the first time, these compounds used to pharmacologically classify the subtypes of P2 purinoceptors are demonstrated to have direct inhibitory effects on purified ecto-ATPase. Therefore, data generated using these compounds on purinoceptors must be interpreted in light of their direct inhibitory effect on the ecto-ATPase found in the same tissues.