[Changes of blood-brain barrier in the ethylnitrosourea induced rat glioma (author's transl)].

Capillary permeability of rat brains bearing ethylnitrosourea induced rat glioma was measured with quantitative autoradiography. In the small tumors (less than 2mm in diameter), no changes in capillary permeability was noted. When tumors became larger and neovascularization of the tumor occurred, increase in capillary permeability was evident. This change was more prominent in the center of the tumor than in the periphery. In the large tumors, the capillary permeability was markedly increases, and the value was similar to that in the choroid plexus. This indicates that blood-brain barrier(BBB) completely disappeared in the large tumors. This BBB change may be the main cause of tumor induced brain edema. The data also provide the information about pharmacokinetics of water soluble drugs in the brain tumors.