Effect of injections of contrast media on regional uptake of (14C)-2-deoxyglucose by the rat brain.

Mechanisms contributing to the rare but consistent neurotoxicity of contrast media currently in clinical use for the radiological examination of the subarachnoid space remain to be isolated. We assessed, by means of the (14C)-2-deoxy-D-glucose (2-DG) autoradiographic method, the effect of three non-ionic, low-osmolar contrast media, namely metrizamide, iopamidol and iohexol, on the local cerebral glucose utilization in the rat brain after intracisternal application. A significant (-30%) global reduction of the brain's metabolic activity occurred following intracisternal metrizamide injection. When compared with the mock-CSF control group the greater relative changes were observed in the supratentorial grey matter structures. In contrast, no significant changes were observed in metabolic brain activity in rats treated intracisternally with iopamidol and iohexol. These findings were consistent with the hypothesis that metrizamide is a competitive inhibitor of human brain hexokinase. The apparent lack of interference on neural tissue metabolism makes the second generation contrast media less neurotoxic and more suitable for neuroradiological subarachnoid investigations in clinical settings. The present experimental work establishes the 2-DG method as a viable laboratory approach to investigate aspects of neuronal dysfunction induced by contrast media.