Detection of Microregional Fluctuations in Erythrocyte Flow Using Laser Doppler Microprobes
It is well established that experimental tumours develop microregions of nutrient-deprived and oxygen-deficient cells as a consequence of their heterogeneous vascular supply. Spatial heterogeneity can lead to the existence of chronically hypoxic cells at a distance from blood vessels, as originally described by Thomlinson and Gray (1955). However, it has also been suggested that a temporal heterogeneity in perfusion could lead to a transient, potentially reversible, acute hypoxia (Brown, 1979). Evidence for temporary non-perfusion of vessels has been provided by direct observation of ‘sandwich’ tumour preparations (Reinhold et al., 1977) as well as by histological techniques which involve the injection of two fluorescent markers, separated in time (Trotter et al., 1989). These perfusion markers have provided evidence of intermittent blood flow in a number of different experimental murine tumours, but they do have limitations; in some systems the dyes themselves are vasoactive, the techniques are not clinically applicable and they provide no kinetic information on the duration of vessel non-perfusion.
KeywordsHypoxic Cell Acute Hypoxia Temporal Heterogeneity Tumour Blood Flow Trace Direction
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