Cerebral blood flow in split-brainstem rabbits

Cerebral blood flow (CBF), mean arterial pressure (MAP) and heart rate (HR) were recorded in anaesthetised, vagotomised, paralysed and artificially ventilated rabbits before and after a mid-sagittal section of the lower brainstem ("split-respiratory centre"). Splitting the medulla elicited first a small decrease and then an increase in CBF, a decrease in HR but no change in MAP. Hypoxia reduced CBF but did not modify MAP or HR. Hypercapnia did not significantly affect any of these parameters. It is concluded that a midline section of the rabbit's medulla and lower pons does not impair CBF and therefore the decrease in output from the respiratory controller, observed in split-brainstem animals, is not likely to be elicited by alterations in CBF.