1993 Volume 14 Issue Supplement Pages 553-556
This study was designed to investigate the effects of low power laser irradiation on vascular smooth muscle in various wavelengths and intensities.
Ring segments of rat thoracic aorta were mounted isometrically with 2g resting tension in 60ml Krebs buffer. Vascular ring precontracted with norepinephrine (1×10-6M) was irradiated with an argon ion laser (351nm, 514.5nm) or a Ti: Sapphire laser (800nm) towards its endothelial surface for 60 seconds via a 200μm core optical fiber. In addition, temperature at the laser-irradiated point was measured.
The 351nm laser irradiation at the power between 2 and 10mW induced vascular relaxation less than 1.0g in each case. The 800nm irradiation at the power over 80nm caused power-dependent contraction less than 0.1g. The vascular segment irradiated with the 514.5nm irradiation showed either power-dependent contraction less than 0.1g or relaxation less than 1.0g at the power more than 160 mW. Tissue-temperature rise was 2.91°C at 351nm irradiation (60mW), 1.90°C at 514.5nm irradiation (500mW) and 3.35°C at 800nm irradiation (600mW).
