Fig. 1.
ADA isozyme sensitivity to EHNA: Duodenal homogenates (•) and macrophage cell lysates (□) were treated in vitro with EHNA concentrations ranging from 10−8 to 5 × 10−4m and adenosine deaminase activity was subsequently determined. Inhibition of ADA activity by EHNA relative to basal activity is shown. There was a dose dependent decrease in ADA activity between 10−7 and 10−4m EHNA. At concentrations higher than 10−4m EHNA ADA activity was below detection limits in duodenal homogenates. In contrast, the inhibition of macrophge cell lysates ADA activity reached a nadir at around 20–30%. The activity that remained represents ADA2 activity.