What can I do when Hypoxyprobe staining patterns do not appear to be consistent with tissue hypoxia?
To date, immunostaining patterns for pimonidazole (Hypoxyprobe) adducts are generally consistent with the presence of tissue hypoxia. However, the British pathologist, Leon Cobb, questioned at one time whether high concentrations of nitroreductase enzymes in the pericentral region of liver, for example, might overwhelm the oxygen inhibition of pimonidazole binding and lead to erroneous conclusions about the presence of hypoxia marker binding around the pericentral vein. We met this important challenge by examining the binding of pimonidazole in the pericentral region of rat livers during normal (anterograde) and reverse (retrograde) perfusion of dissected livers. Reverse perfusion causes liver regions around the pericentral vein to become oxygenated and those around the portal vein to become hypoxic. If high concentrations of redox enzymes in the pericentral region caused pimoindazole binding in the presence of oxygen then we would expect to see high levels of pimonidazole binding in t
