Ectonucleotidase activity in the effluents of immediately after reperfusion. (A) Effluents collected as indicated in Figure 3 were incubated with 100 μM ATP, AMP or adenosine (Ado) for 10 or 30 min, and the decrease in each substrate was measured by HPLC. All values are means ± S.E.M (n = 5)Enzyme activities are shown as nmole substrate hydrolyzed by 1 ml effluent for 1 min. All values are means ± S.E.M (n = 5). Lower panels show typical HPLC chromatograms of ATP (B) and AMP (C) hydrolyzed by the first fraction of post-ischemic reperfusate.