Low-Power Laser Irradiation Increases Cyclic GMP Synthesis in Penile Smooth Muscle Cells in Vitro

Objective: The objective of the present study was to determine the effect of low-power laser irradiation (LPLI) on cyclic guanosine monophosphate (cGMP) produced by human corpus cavernosum smooth muscle cells (HCC SMC) in vitro. Background Data: Numerous reports suggest that LPLI is capable of affecting cellular processes in the absence of significant thermal effect. Methods: HCC SMC cultures were irradiated with single-dose LPLI using a He-Ne continuous wave laser (632 nm) with different energy densities (0.52–2.1 J/cm²). Assessment of effect on cell viability was performed utilizing Alamar Blue assay. Effect of LPLI on cGMP production was studied by radioimmunoassay. Results: We observed that: (1) LPLI of HCC SMC results in a statistically significant increase of cGMP synthesis in culture and is dose dependent (maximal effect was observed with LPLI irradiance of 1.57 J/cm². (2) There were no changes in Normalized Viability Index (NVI) immediately after and 24 h following laser irradiation. Conclusion: Our studies demonstrate that LPLI irradiation stimulates elevation of cGMP in vitro.