Intravenous adenosine selectively increases blood flow to xenotransplanted intracerebral gliomas

Adenosine was infused intravenously at 10 mumol/(kg.min) into athymic ("nude") rats with intracerebral D-54MG xenotransplanted brain tumors, in an attempt to increase tumor blood flow. Cerebral blood flow (F) was measured with 14C-iodoantipyrine and quantitative autoradiography. Mean arterial blood pressure was 95 +/- 9.4 (SE) mm Hg in the adenosine group and 112 +/- 6.0 mm Hg in the controls. Averaged mean whole tumor F was significantly higher in adenosine-treated brain tumors (117.6 +/- 20.8 ml/[hg.min]) than in controls (62.2 +/- 9.7 ml/[hg.min]). Regionally, there were significant increases of F in tumor periphery and brain around tumor, but not in tumor center or any tumor-free brain regions. Focal values of F less than 5 ml/(hg.min) were present in some necrotic regions of adenosine-treated tumors. These results, obtained in unanesthetized rats with transplanted gliomas from a human cell line, confirm our earlier observations in avian sarcoma virus-induced brain sarcomas in dogs, and suggest that adenosine or perhaps other vasodilators could be used to selectively increase the delivery of lipid-soluble chemotherapeutic drugs to brain tumors.