Possible mechanisms of vascular relaxation induced by pulsed-UV laser.
This study was designed to examine the mechanism of vasorelaxation induced by pulsed-UV laser. Luminal diameters of rat femoral arteries were measured prior to and following krypton-fluoride excimer laser irradiation of 248 nm in wavelength. The diameter was enlarged to 1.3 times the preirradiated size at 1 or 10 Hz irradiation when the fluence was over 2.0 mJ/pulse/mm2, while the diameter reached 1.8 times at 100 Hz with a fluence of 0.8 mJ/pulse/mm2. Vasorelaxation by the 100 Hz irradiation was inhibited when the artery was pretreated with methylene blue but was enhanced with superoxide dismutase. Pathological analysis revealed an ablation crater and vacuole formation in the vessel at 1 or 10 Hz irradiation, but these changes were not remarkable in the 100 Hz-exposed sample. These findings suggest that vasorelaxation induced by the pulsed UV irradiation at 1 or 10 Hz results from structural alteration of vascular smooth muscle by the ablation crater or vacuolization. On the other hand, a possible mechanism of vasorelaxation at the 100 Hz irradiation is partially related to nitric oxide.
Morimoto
Y
Y
Department of Medical Engineering, National Defense Medical College, Saitama, Japan. moyan@interlink.or.jp
Arai
T
T
Matsuo
H
H
Kikuchi
M
M
D000818:Animals; D005263:Femoral Artery / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure; D007834:Lasers; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000494:pharmacology; D014466:Ultraviolet Rays; D014617:Vacuoles / Q000187:drug effects / Q000528:radiation effects; D014664:Vasodilation / Q000187:drug effects / Q000528:radiation effects*
D013482:Superoxide Dismutase; D008751:Methylene Blue