Comparison of methods eliciting cerebral ischaemic pressor response in the cat

Three methods of intercepting the blood supply to the brain were tested by means of X-ray angiography and by monitoring the pressor response following cerebral ischaemia. The methods were: (1) occlusion of carotid and basilar artery; (2) occlusion of carotids and vertebral arteries in the cervical canal of the third vertebra; (3) occlusion of carotid and subclavian arteries. The X-ray angiographs showed that in most cases we could close the accessory sources of the cerebral circulation and drastically reduce the blood supply to the brain of the cat. With all three methods the cerebral ischaemia evoked strong blood pressor elevation, which was weaker however when the carotid and basilar artery were clamped, in comparison with the other two methods. This may be explained by the existence of small arteries supplying the lower brain stem and originating intracranially from the vertebral artery near to the junction of the vertebral and anterior spinal artery.