Experimental vasospasm: experiences with a canine model and failure of naloxone therapy.

Experimental vasospasm was studied in a canine model utilizing subarachnoid injection of autologous blood. Alterations in the size of the basilar artery were noted angiographically. Naloxone, an opioid receptor antagonist, has been reported to have a beneficial effect on neurological dysfunction secondary to cerebral ischemia. No significant change in the diameter of the basilar artery was noted in dogs either with or without spasm when treated with naloxone. We have concluded that naloxone has no detectable vasodilatory effect on the cerebral arteries of dogs.