Figure 3.

A and B, superfusate application of 300 nm and 3 μm α,β-meATP, a selective P2X1 receptor agonist, evoked both transient and sustained vasoconstriction. C, pretreatment with the P2X1 antagonist NF023 (10 μm) abolished vascular responses to α,β-meATP (300 nm). Bars represent application intervals. D, summary data for 300 nm α,β-meATP applied alone (peak and sustained) and after pretreatment with NF023 (10 μm). Note that in contrast to in vivo experiments, NF023 applied ex vivo did not produce dilatation because vessels in the isolated retina lack tone. Numbers in parentheses represent number of retinal preparations (minimum of three animals). *P < 0.05, ***P < 0.001, relative to baseline. α,β-meATP, α,β-methylene ATP; NF023, 8,8′-[carbonylbis(imino-3,1-phenylenecarbonylimino)]bis-1,3,5-naphthalene-trisulphonic.