Does Hypoxyprobe-1 detect both chronic and acute hypoxia?
Two categories of hypoxia are currently recognized in solid tissues diffusion-limited chronic hypoxia and perfusion-limited acute hypoxia. Chronic hypoxia arises at the distal end of oxygen gradients created by oxygen consumption in cells close to blood vessels compounded, in the case of tumors, by deficiencies in local oxygen supply arising from longitudinal gradients of pO2 in vascular trees (54). The presence of chronic hypoxia implies that cells in tissues consume oxygen at a rate that is independent of oxygen supply thereby driving pO2 to very low levels in microregions distal to blood vessels. That is, most cells possess characteristics of a regulating cellular phenotype that is preprogrammed to adapt to low pO2 by smoothly transitioning to glycolytic based energy production (55). In contrast to chronic hypoxia with static, metabolically controlled pO2 gradients, acute hypoxia is associated with fluctuating pO2 that results from blood flow instabilities which, in the case of tumo
