The response of cerebral blood flow (CBF) during isocapnic hypoxic hypoxia was studied in 1-7 day old lambs that underwent sinoaortic chemodenervation. Lambs were anesthetized with pentobarbital and studied during moderate (arterial O2 content [CaO2] =10 vol %) and severe (CaO2 =6 vol %) hypoxic hypoxia. Regional brain blood flows were measured with the radioactive microsphere technique. Cerebral oxygen consumption (CMRO2) was calculated as the product of forebrain blood flow and the difference in oxygen content between arterial and sagittal sinus blood. Lambs were then subjected to either sham surgery (n=6) or to carotid chemodenervation and cervical vagotomy (n=6). Chemodenervation was verified by abolition of the transient increase in blood pressure following intravenous injection of sodium cyanide in intact subjects. Neither sham surgery nor chemodenervation had any effect on CBF or CMRO2 during hypoxic hypoxia. These data show that arterial chemoreceptors have no role in the regulation of cerebral vascular tone during hypoxic hypoxia in the 1-7 day old anesthetized lamb
