Monitoring Metabolite Gradients in the Blood, Liver, and Tumor after Induced Hyperglycemia in Rats with R3230 Flank Tumors Using Microdialysis and Bioluminescence Imaging

Abstract

Hypoxia is a common cause of reduced tumor response to treatment such as irradiation. The purpose of this study was to establish a method in a rat model that is clinically applicable to monitor the efficiency of glucose transport to both tumor and normal tissue following the induction of hyperglycemia. Female Fischer 344 rats bearing subcutaneous R3230 rat mammary adenocarcinomas received glucose (1 g/kg in 200 mg/ml Normosol) injected in the femoral vein with an infusion pump at a rate of 0.1 ml/min. Microdialysis sampling was performed on all animals. The perfusion marker Hoechst 33342 was injected intravenously at a dose of 5 mg/kg ten minutes prior to sacrifice. After the last blood sample was collected, the tumor and liver were removed and snap frozen for bioluminescence imaging and the rat was sacrificed. Imaging bioluminescence was performed on cryosections of the tumor and liver of the animal to monitor local metabolite gradients and concentrations of glucose in relation to the perfused vasculature, as determined by injected Hoechst 33342. Microdialysis and bioluminescence show comparable data when monitoring the changes of blood, liver, and tumor glucose concentrations as a result of induced hyperglycemia.