<p>A: Effect of suramin on an oocyte expressing wild type rP2X2 when applied without exogenous ATP. The horizontal dashed line indicates the 0 current level. B: Correlation between the initial holding current of oocytes expressing wild type rP2X2 and the amplitude of the outward current in response to suramin (20 µM) or apyrase (1 mg/ml) C: Average amplitude of the outward current in response to suramin, apyrase, or recording solution alone applied from a separate barrel of the solution switcher (control). D: Effect of suramin on an oocyte expressing K69C before AM546 (thin gray trace) and after AM546 (thick black trace). The two traces were <i>not</i> baseline corrected to indicate the drop in holding current caused by AM546 (vertical dashed line). E: Concentration-response plots of suramin on wild type rP2X2 and AM546-treated K69C receptors (N = 6). F: Response of a K69C oocyte to 200 µM suramin after treatment with AM546 and then retested after exposure to MTSES. G: Results of a series of experiments as in F. The “AM546 after MTSES” group represents a control to verify that the dose of MTSES given to the “MTSES after AM546” experimental group was sufficient to occupy all free cysteines.</p
