The Effect of Prolonged Ischemia upon Regional Energy Reserves in the Experimental Glioblastoma1

Changes in levels of known anaerobic energy reserves [glucose, glycogen, adenosine triphosphate (ATP), and phosphocreatine and lactic acid] have been determined in microgram quantities of three different but homogeneous cytologie zones of the experi mental glioblastoma during prolonged ischemie incubation. Xormal murine white matter was studied under identical conditions. Lightly anesthetized white matter, once rendered ischemie, rapidly cleaves glucose and glycogen to form lactate in quantities expected from anaerobic hexose degradation, and in addition rapidly exhausts endogeneous ATP and phosphocreatine reserves. Peripherally situated cells of the ischemie experimental glio blastoma produce lactate in significant excess to that expected from measured hexose degradation, and in addition maintain low but readily measurable levels of ATP despite prolonged incuba tion. The rate of expenditure of energy reserves (metabolic rate) is several fold greater at the tumor periphery in comparison to the tumor core. Observations made at the microchemical level provide experimental confirmation for certain theoretic models which have been formulated to explain the observed growth rates of transplanted experimental tumors.