CEREBRAL BLOOD-FLOW IN A RAT GLIOMA MODEL DURING HALOTHANE ANESTHESIA

Little is known about the influence of infiltrating gliomas on the res ponsivity 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 grou ps, glioma cells were stereotactically injected into the right striatu m, animals in the sham group were injected with sterile culture medium only. Either 12 or 16 days after injection. the rats were anesthetize d with 1 MAC halothane in 40% O2/balance N2. Local and remote regional cerebral blood flow was then determined using C-14-iodoantipyrine aut oradiography. Physiologic values (PaCO2, PaO2, pHa, mean arterial pres sure, and rectal temperature) were similar for both tumor and sham gro ups. Tumor volume was relatively small (cross-sectional diameter = 2-3 mm), and there was no evidence of midline shift in coronal tissue sec tions. 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 differe nces between the tumor and sham groups for regional blood flow values in histologically normal tissue in either the injected or contralatera l hemispheres. We conclude that this model of brain neoplasia shows no evidence of either local or remote changes in the cerebrovascular res ponsibility of normal tissue to volatile anesthesia.