Improved neurological outcome in experimental focal cerebral ischemia treated with propranolol

Propranolol has been shown to exert a protective effect in experimental myocardial, renal, and early acute focal cerebral ischemia. However, propranolol was not found to reduce infarct size in nitrous oxide-anesthetized, paralyzed, mechanically ventilated cats subjected to 6 hours of acute focal ischemia. The objective of the current investigation was to study further the effects of racemic (d,l)-propranolol on the evolution of acute focal cerebral ischemia in awake, conscious cats. Adult cats were anesthetized with halothane and underwent the implantation of an occluding device around the right middle cerebral artery. After a 48-hour recovery period, the right middle cerebral artery was occluded for 6 hours and then reopened, allowing reperfusion for an additional 6 hours. Neurological examinations were conducted every 2 hours throughout each experiment. Ten cats received d,l-propranolol (2 mg/kg) 1 hour before occlusion, immediately before occlusion, and every 2 hours throughout each experiment. Eleven cats serving as controls were not treated. The neurological examination significantly improved over time in the treated group when compared to the untreated group (P = 0.01). Carbon filling defects, gross brain swelling, and infarct size were reduced in treated cats. The results of this study suggest that propranolol does have beneficial effects in acute focal cerebral ischemia.