Key Process Of Cellular Photo-Biomodulation Of Low Intensity Laser Irradiation

Background and Objective: There is little research on the dynamics ofphotobiomodulation (PBM) although its phenomena and mechanism have beenwidely studied. The primary process of cellular PBM of low intensity laser irradiation(LIL) is the interaction of LIL with a kind of molecules of a cell. The dynamics ofcellular PBM of LIL (LPBM) was studied from the viewpoint of its primary processin this thesis. Study Methods: The key process of cellular LPBM was studied bymeans of comparison of the transition rate of its primary process with its doserelationship after reviewing cellular LPBM. Cultured normal human skin fibroblasts(HSFs) were treated by low intensity He-Ne laser irradiation (LIHL) with differentintensity and the same irradiation time. Cultured NIH 3T3 fibroblasts (NTFs) weretreated by low intensity 810nm GaAlAs diode laser irradiation (LIGL) with the samedose but different intensity. The cell proliferation and collagen synthesis wereevaluated by using of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay and the spectrophotometric method for the determination ofhydroxyproline, respectively. Results: 1. The dose zones of LIHL effects on HSFswere called dose 1, dose 2 and dose 3 from low dose on, respectively, so that HSFproliferation was inhibited in dose 1, and promoted in dose 2, and the collagensynthesis was inhibited in dose 2, and promoted in dose 3. 2. The effects of LIHLwere lineally related to its intensity when the radiation time was kept constant, butthere was an optimum radiation time when the radiation dose of LHGL was keptconstant. It was also found that the optimum radiation time was independent of theradiation dose or intensity when the LIL had the same wavelength and the samecellular function was modulated. 3. The primary process of cellular LPBM wassupposed to be the key process after reviewing cellular LPBM, which was supportedby above experimental results. Conclusions: The primary process of cellular LPBMmight be the key process, and the transition rate equation of the primary processmight be used to study the dose relationship of cellular LPBM. When the radiationtime of LIL is constant, the cellular LPBM might be lineally related to irradiation dose or intensity. When the dose of LIL is constant, the reciprocity rule might nothold so that there is an optimum irradiation time.