Chemical regulation of the cerebral blood flow in cats with rostro- or prepontine transection of the brainstem.

Cerebral blood flow (CBF) and its response to hypercapnia were evaluated in cats with brainstem transected either at rostropontine (pretrigeminal preparation) or prepontine (cerveau isole preparation) level. Additionally, the effect of pentobarbital on CBF response to hypercapnia and to papaverine were examined. CBF was measured with 133 Xe intracarotid injection method. Cortical EEG activity was recorded. In rostropontine cats cerebral vessels responded with a dilatation to hypercapnia. In prepontine cats CBF response to CO2, was absent, where-as that to papaverine maintained. In rostropontine cats administration of pentobarbital, even in very low doses, caused disappearance of CBF response to hypercapnia, leaving that to papaverine. Our results support the idea that a neurogenic mechanism is involved in chemical regulation of CBF. The rostra1 part of the pontine reticular formation may be responsible for this neurogenic control.