Abstract
Present study was conduced to investigate the effects of direct irradiation of low energy laser (LEL) on the contraction of rat thoracic artery smooth muscle. Helical strips of thoracic artery isolated from male Wistar rats (5-6 weeks ord) were mounted isometrically (0.5g) in 30ml of Crebs-Henseleit solution (37°C). Norepinephrine (NE: 2-5nM)-or KCl (5-10mM)- induced contractions were recorded using a modified Magnus method. To irradiate the LEL (Ga-Al-As laser, 21mW, 830nm) on the strips directly, Magnus tube was pulled down and the strips were exposed in the air for ten or one minute. Soon after the irradiation was over, the tube was replaced. Three minutes after the replacement, NE or KCl was applied in the bath.
The ten minutes irradiation of LEL on NE-induced contraction made the rate of contraction at the starting phase faster, though no significant change was seen in peak tension or oscillatory movement. On KCl-induced contraction, LEL showed tendency to reduce the peak tension but no significant effect was found.
