TISSUE OXYGENATION AND NORMAL AND HYPERTHERMIC CONDITIONS

Abstract

This chapter describes the tissue oxygenation and normal and hyperthermic conditions. The knowledge of the effect of hyperthermia on tumor and normal tissue blood flow is important not only for the effect of hyperthermia on hypoxic cells at the time of radiation, but also for differential tumor heating. There is considerable evidence from plethsmography that an elevation of normal tissue temperature to 41°C is accompanied by a considerable increase in blood flow. The chapter discusses studies that were conducted to examine changes in the microenvironment of normal and tumor tissue as measured directly with ultramicroelectrodes. In situ studies were carried out in fourth generation transplants of C3H mammary adenocarcinoma implanted in the hind leg of C 3 H SED-BH mice. This was a syngenetic implantable tumor that was kept at facility using solid tissue transplants that were inocculated subcutaneously into recipient mice. Tumors used for experimentation were approximately 10 mm in diameter. It is clear that blood flow increases significantly up to approximately 41°C. In addition, the examination of the data shows the strong correlation between decreases in TpO 2 and blood flow as the temperature is increased up to 45°C. By employing eight different animals with implanted tumors, a large number of single point pH determinations were made both prior to and following hyperthermia.