Oxygenation of malignant tumors after localized microwave hyperthermia.
The oxyhemoglobin saturation (HbO2) of single red blood cells within tumor microvessels (diameter: 3-12 micrometers) of DS-Carcinosarcoma was studied using a cryophotometric micromethod. In untreated control tumors (mean tissue temperature approx. 35 degrees C) the measured values scattered over the whole saturation range from zero to 100 sat. %, the mean being 51 sat. %. Upon heating at 40 degrees C for 30 min, the oxygenation of the tumor tissue significantly improved as compared with control conditions. After 40 degrees C-hyperthermia a mean oxyhemoglobin saturation of 66 sat. % was obtained. In contradistinction to this, after 43 degrees C-hyperthermia the tumor oxygenation was significantly lower and reached a mean HbO2 saturation value of 47 sat. %. A further temperature rise to 45 degrees C caused the oxygenation to drop drastically (mean oxyhemoglobin saturation value: 24 sat. %). This is due to a severe restriction of nutritive blood flow. The changes in tumor oxygenation after hyperthermia seem to be predominantly mediated through changes in tumor blood flow, including tumor microcirculation, which showed a similar temperature dependence. Metabolic effects probably play a minor role in the oxyhemoglobin saturation distribution within tumor microvessels.
D000818:Animals; D002296:Carcinosarcoma / Q000098:blood supply* / Q000628:therapy; D004912:Erythrocytes / Q000378:metabolism* / Q000528:radiation effects; D005260:Female; D006358:Hot Temperature / Q000627:therapeutic use*; D008297:Male; D008872:Microwaves / Q000627:therapeutic use*; D010108:Oxyhemoglobins / Q000378:metabolism* / Q000528:radiation effects; D051381:Rats; D011919:Rats, Inbred Strains; D012513:Sarcoma, Experimental / Q000098:blood supply* / Q000628:therapy*
D010108:Oxyhemoglobins