Electrophysiologic effect of Gallium arsenide laser on frog gastrocnemius muscle

Background and Objective: In this study, the effect of low energy Gallium arsenide (GaAs) laser irradiation on the compound action potential of frog gastrocnemius muscle were investigated. Study Design/Materials and Methods: Sixty frogs were divided into different six dose groups: laser 1 (1 Hz), laser 2 ( 4 Hz), laser 3 (16 Hz), laser 4 (64 Hz), laser 5 (128 Hz), and laser 6 (1,000 Hz, DC, continue) (in each group n = 10). Low energy GaAs laser (wavelenght: 904 nm, pulsed duration: 220 nanoseconds, peak power per pulse: 27 W, total applied energy density: 0.001-25.7 J/cm(2)) was used for the experiment. Compound muscle action potentials were recorded before laser irradiation and these data were accepted as control group. After recording the control data, each muscle was irradiated by the laser. Action potentials were recorded at 1, 5, 10, 15, and 20 minutes of irradiation time in each group by using standartized needle electromyography and nerve conduction study techniques. Distal motor latency, peak to peak amplitude, area, and total duration of action potential were measured. Repeated measures analysis of variance were used for the statistical evaluation. Results: No significant differences were detected between control and laser dose groups in muscle action potential parameters. Conclusions: This study revealed that at the different repetition rate and exposure time, low energy GaAs laser does not have any significant effect on frog gastrocnemius action potential. Lasers Surg. Med. 30:221-226, 2002. (C) 2002 Wiley-Liss, Inc.