Temporal heterogeneity in microregional erythrocyte flux in experimental solid tumours

Sary Using a multichannel laser Doppler system equipped with custom-developed microprobes, we have evaluated real-time fluctuations in microregional blood flow in two experimental murine tumour systems. The results show that in both the sarcoma F and the carcinoma NT over 50 % of the microregions evaluated show a fluctuation in red blood cel flux by at kast a factor of 2 over a 60 min time period. Approximately 20 % of the regions monitored demonstrated a change in flow by a factor of 5 or more. Within the I h monitoring period, approximately 20 % of the changes were reversed (SaF, 21%; CaNT, 19%). The duration of change for these regions ranged from 6 to 45 mm. Similar temporal fluctuations in flow were seen in anacsthetised and unanesthetised animals, incating that artifacts due to probe movement were minimal. These findings cearly demonstrate that fluctuations in microregional erythrocyte flux are a common feature of tbe experimental tumours studied. Keywords microregional blood flow; erythrocyte flux; tumour oxygenation; laser Doppler It was nearly 40 years ago that Thomlinson and Gray (1955) first focused radiation biologists ' and therapists ' attention on the profound effects that hypoxia has on cellular response to radiation. Subsequent studies in the 1970s and 1980s demon-strated that the level of oxygen in which cells are grown can alter their responsiveness to a number of chemotherapeutic agents (Teicher et al., 1981). Even more recently, the pro-found effects that hypoxia can have on the actions of cyto-kines, including interleukin 2 (IL-2), tumour necrosis factor alpha (TNF-a) and interferon (IFN), have been describe