Abstract
In a search for the simplest technical variations of photothrombosis we employed a krypton laser to induce photothrombotic cortical infarction in rats. The cortical region was irradiated by krypton laser transmission through the skull. The photosensitizing dye, rose bengal, at a body dose of 20 mg/kg was administered intravenously at a time interval of 90 sec. We confirmed reproducible infarction at laser powers of 5, 10 and 20mW, but not at 2mW. The rise in brain cortical temperature during irradiation with the laser beam applied directly to the cortex at 7 mW, which corresponds to 10mW used through skull, was less than 2°C; this was thus likely to avoid epiphenomena due to excess heat absorption. The advantages of our method may be summarized as follows. Highly reproducible infarcts can be produced, even though the model does not entail extensive surgery or opening of the skull. The 568-nm krypton laser does not require a high maintenance dye laser. Producing bilateral cortical intraction is also feasible. This thrombotic model affords useful standards for assessing the effects of antiplatelet treatment.
