QUANTITATIVE CHANGES IN COLLAGEN LEVELS FOLLOWING 830-NM DIODE-LASER WELDING

Background and Objective: The actual mechanism by which laser irradiat ion welds tissue is presently unknown; however, collagen is a major co nstituent of tissue welded by laser irradiation. Study Design/Material s and Methods: Collagen was extracted from the abdominal aorta of Wist ar rats by acetic acid extraction and repeated pepsin digestion after tissue welding (254 W/cm(2)) by using an 830-nm diode laser. The colla gen levels were determined by using the Sircol Collagen Assay (Biocolo r, Northern Ireland). Results: Compared with untreated aorta, the coll agen content of the treated vessel was obvious decreased (P < 0.001) i mmediately after laser irradiation. Levels then increased by day 3, wi th a peak at day 10 (P < 0.002). The collagen content returned to norm al levels on day 30 and remained at this level throughout the rest of the experimental period. Conclusion: These results suggest that a prop ortion of the collagen molecules in the vessel are denatured by the he at of the laser. Collagen synthesis is stimulated during the healing p rocess after laser welding with the parameters used in the present stu dy. (C) 1998 Wiley-Liss, Inc.