Cerebral blood flow in a rat glioma model during halothane anesthesia

Little is known about the influence of infiltrating gliomas on the responsivity of the cerebral circulation to anesthetic agents. Therefore we designed a study to address this issue. Male Fischer 344 rats were assigned to two tumor groups and one sham group. In the two tumor groups, glioma cells were stereotactically injected into the right striatum; animals in the sham group were injected with sterile culture medium only. Either 12 or 16 days after injection, the rats were anesthetized with 1 MAC halothane in 40% O₂/balance N₂. Local and remote regional cerebral blood flow was then determined using ¹⁴C-iodoantipyrine autoradiography. Physiologic values (PaCO₂, PaO₂, pHa, mean arterial pressure, and rectal temperature) were similar for both tumor and sham groups. Tumor volume was relatively small (cross-sectional diameter = 2-3 mm), and there was no evidence of midline shift in coronal tissue sections. Blood flow within the tumor was substantially reduced relative to adjacent structures (e.g., tumor = 88 ± 10 ml/100 g/min; adjacent caudate = 161 ± 23 ml/100 g/min). There were no significant differences between the tumor and sham groups for regional blood flow values in histologically normal tissue in either the injected or contralateral hemispheres. We conclude that this model of brain neoplasia shows no evidence of either local or remote changes in the cerebrovascular responsibility of normal tissue to volatile anesthesia.