Yag laser-induced reperfusion of photothrombotic middle cerebral artery occlusion in rats

The laser-driven photochemical occlusion of middle cerebral artery (MCA) is much easier and less traumatic than standard electrocautery or even clip methods, while the infarct size is fairly reproducible. This study aimed to establish the system for YAG laser-induced reperfusion of photothrombotic MCA occlusion. Male spontaneously hypertensive rats (5-7 months old, 350-450 g) were anesthetized with halothane, endotracheally intubated, and mechanically ventilated. The photosensitizing dye rose bengal (20 mg/kg body weight) was administered intravenously over 90 sec starting simultaneously with 3 min of krypton laser irradiation (568 nm, 20 mW). The irradiated middle cerebral artery was completely occluded by an intraluminal thrombus. A YAG laser operating at 355 nm (16 mW, 15 Hz) was focused with a cylindrical lens and positioned with a mirror onto the occluded distal MCA. This YAG laser irradiation for approximately 3 min caused reperfusion of the thrombosed distal MCA. We demonstrated a novel method of reperfusion in the photothrombotic MCA occlusion model. This reperfusion model should facilitate study of the therapeutic window for reversibility in thrombotic stroke.