Biochemical mechanisms of laser vascular tissue fusion.

This study examines the biochemical changes that occur in argon laser-fused canine veins compared with control segments of vein. Laser fusions were formed using 0.5 W argon laser energy (1100-1500 J/cm2). Immediately following tissue fusion, blood flow was reestablished to test the integrity of the welds. 1-mm3 sections of the anastomoses and control sections were minced and protein extraction was performed by solubilizing the tissue in hot SDS Laemmli gel sample buffer. The proteins were separated electrophoretically on 5 and 10% polyacylamide SDS gels and silver stained. The analysis demonstrated significant biochemical differences between control and lased veins. We noted increases in several proteins after laser welding: the putative beta chain of type V collagen (5/5 gels), the putative gamma chain of type I collagen (4/5 gels), a 156-kDa protein (based on collagen molecular weight standards) 7/7 gels), an 82-kDa protein (8/9 gels), and several proteins of lower molecular weight (3/8 gels). The increases may be due to crosslinking of lower molecular weight proteins, degradation of higher molecular weight proteins, or increased solubility of certain proteins. These findings suggest that laser welding may occur by formation of crosslinks or by denaturation and reannealment of structural proteins.