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 ischaemia in rats. Changes in blood flow in the spinal cord were assessed by laser Doppler flowmetry. The Th11 spinal cord segment was irradiated by an argon ion laser after intravenous injection of an organic dye, erythrosin B, to rats with or without a laminectomy. In the group of laminectomized rats, laser irradiation for 5 s did not influence cord 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 cord blood flow were noted after 20 s and after 1 min of laser irradiation, respectively, with no recovery observed after 20 min. In the group of rats without a laminectomy, 1 min of laser irradiation caused approximately a 25% decrease of spinal cord blood flow, which gradually recovered within 12 min, whereas 5 min of laser irradiation caused a more 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 regional spinal cord blood flow and the extent of this effect could be modified by varying the duration of laser irradiation. The present results therefore provide further support for using this photochemical technique to create animal models of central nervous system ischaemia.