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RESEARCH PRODUCT

HETEROGENEOUS OXYGEN TRANSPORT WITHIN MALIGNANT TUMORS

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Publisher Summary This chapter discusses the heterogeneous oxygen transport within malignant tumors. Many solid tumors disturbances in the vascularization and in the microcirculation generally lead to distinct restrictions in the convective and diffusive transport. Beyond that, a heterogeneous distribution of the transport conditions develops causing an insufficient and heterogeneous substrate supply as well as an inadequate drainage of wastes. As one of the compulsory manifestations, a poor and heterogeneous oxygen supply becomes more extensively evident with increasing tumor size or age. The polarographic measurements of the local tissue pO 2 values in animal tumors show that very low oxygen partial pressures are prevalent. The tissue pO 2 frequency distributions are shifted to low pO 2 values and are limited in variability. There are pronounced heterogeneities within the same tumor looking at different microelectrode tracks. This is valid for both the rat and the mouse tumor. The determination of the intracapillary HbO 2 saturation values show that very low saturations are prevailing in the tumor tissue. Regional differences can only be found in those areas where a sufficient vascularization still exists.