PHOTOCHEMICALLY INDUCED SPINAL-CORD ISCHEMIA IN RATS - ASSESSMENT OF BLOOD-FLOW BY LASER-DOPPLER FLOWMETRY

A photochemical technique was used to create central nervous system is chaemia in rats. Changes in blood flow in the spinal cord were assesse d by laser Doppler flowmetry. The Th11 spinal cord segment was irradia ted by an argon ion laser after intravenous injection of an organic dy e, erythrosin B, to rats with or without a laminectomy. In the group o f laminectomized rats, laser irradiation for 5 s did not influence cor d blood flow, but 10 s irradiation caused a 25% decrease of blood flow , which normalized within 20 min. Decreases of 50 and 80% in spinal co rd blood flow were noted after 20 s and after 1 min of laser irradiati on, respectively, with no recovery observed after 20 min. In the group of rats without a laminectomy, 1 min of laser irradiation caused appr oximately a 25% decrease of spinal cord blood flow, which gradually re covered within 12 min, whereas 5 min of laser irradiation caused a mor e severe reduction of spinal cord blood flow (45%) with some recovery was observed 30 min later. We could thus confirm that the interaction between a photosensitizing dye and laser irradiation reduced the regio nal spinal cord blood flow and the extent of this effect could be modi fied by varying the duration of laser irradiation. The present results therefore provide further support for using this photochemical techni que to create animal models of central nervous system ischaemia.