Relationship between of blood flow, glucose metabolism, protein synthesis, glucose and ATP content in experimentally-induced glioma (RG1 2.2) of rat brain.

In experimental RG1 2.2 glioma of rat brain, local blood flow, glucose utilization, protein synthesis, glucose and ATP content were measured by means of triple tracer autoradiography and bioluminescence technique, respectively, to determine hemodynamic and metabolic thresholds for local tumor energy failure. Perfusion thresholds were estimated at tumor blood flow values of 69.0 +/- 0.1 ml/100 g/min (estimate +/- standard error) and of 69 +/- 7.1 ml/100 g/min for the beginning of the decline in regional ATP and glucose content, respectively. Metabolic thresholds were derived at tumor glucose utilization values of 70.6 +/- 8.3 mumol/100 g/min for reduced protein synthesis, of 55.0 +/- 0.2 mumol/100 g/min for the decrease in glucose content, and 34.7 +/- 4.7 mumol/100 g/min for decline in ATP content. Our results suggest that blood flow limits glucose supply to tumor tissue at much higher flow rates than in normal brain which, in turn, is associated with a decrease in tumor glucose utilization. A reduction and not an increase in tumor glucose availability could be a more appropriate strategy for the induction of energy failure in tumors.