Is Hypoxyprobe -1 the best probe for detecting hypoxia in vivo?
Hypoxyprobe -1 has some real advantages as a hypoxia marker. Foremost is its high solubility in aqueous solution (400 millimolar; 116 mg/mL of saline) which allows the marker to be administered to rodents as small volume injections of saline solutions (0.1mL) either intraperitoneally or intravenously. Markers such as the hexafluorinated CCI-103F have aqueous solubilities of 10 millimolar or less and are usually administered as intraperitoneal emulsions of peanut oil and DMSO in order to avoid hemodilution (45). Although Hypoxyprobe -1, the hydrochloride salt of pimonidazole, is very water soluble, pimonidazole itself has an octanol-water partition coefficient of 8.5 and penetrates all tissues including brain (see above). Another advantage is that pimonidazole binding can be detected by immunofluorescence in frozen fixed tissue sections; by immunoperoxidase in formalin fixed paraffin embedded tissue sections; by ELISA or by flow cytometry.
