Regional measurements of blood-to-tissue transport in experimental RG-2 rat gliomas.
Regional measurements of blood-to-tissue transport were performed in transplanted RG-2 rat gliomas using [alpha- 14C]aminoisobutyric acid (AIB), quantitative autoradiography, and equations to express a unidirectional transfer constant. Thirty-eight intracranial tumors in ten rats were analyzed according to location; 23 intraparenchymal tumors, eight meningeal tumors, six fourth-ventricular tumors, and one third-ventricular tumor were studied. Except for the small third-ventricular tumor, the transfer constant (K) for AIB was similar in all groups and ranged from 0.031 to 0.038 ml/g/min. Within individual tumors, regional variation of K was also small, although some local variation could be correlated with histological features. The K for AIB decreased in brain around tumor and, at a distance of 300 microns from tumor edge, had returned to values similar to those of normal cortex (0.002 ml/g/min). An average extraction fraction (E) of 0.09 was calculated for AIB in the RG-2 tumors. The low E suggests that delivery of water-soluble chemotherapeutic drugs to RG-2 tumors should be limited more by capillary permeability or surface area than by blood flow. RG-2 is an ideal experimental tumor with which to test drug delivery and the methods that attempt to increase drug delivery in brain tumors.
D000621:Aminoisobutyric Acids / Q000032:analysis; D000818:Animals; D001345:Autoradiography; D001812:Blood-Brain Barrier; D001932:Brain Neoplasms / Q000098:blood supply / Q000378:metabolism*; D002199:Capillary Permeability; D002552:Cerebral Ventricles; D005910:Glioma / Q000098:blood supply / Q000378:metabolism*; D007700:Kinetics; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D000621:Aminoisobutyric Acids