“… anthraquinone derivatives were found to act … positive modulators of ATP effects at P2X2 receptors, for example, sodium 1-amino-4-(3-phenoxyphenylamino)-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (…, PSB-10129, EC(50) 489 nM), which led to about a 3-fold increase in the ATP-elicited current.”