Experimental physiology of photoinduced vasorelaxation using focussed high power LED-irradiation compared to LASER light application

Full text: A photomechanic setup for studying light induction phenomena on vascular epithelial tissue is presented. Ex-vivo artery rings are mounted by vertical strings and force-transducers, which allow to adjust tensile strength of the prepared tissue sample within an organ bath. The ring is immersed within a glass-organ bath and perfused by modified Krebs-Henseleit buffer solution. Arteries are illuminated through the transparent cylindrical double-wall of the organ bath. Two sources are used: a semiconductor laser (HELBO) tuned to operate at wavelength of 690 nm with an output of 400 mW or 100 mW per cm2 alternatively or a non coherent light source (project office HG Loew, Vienna ) that emitted focussed athermic red light at 670 nm with 20 mW per cm2 irradiance; Exposure times of high power LED is performed for 56 s with calculated energy density of 10 joule per cm2. Laser light is applied for 28 s to achieve equal energy density at the surface of the treated vessel-tissue. The resulting vasorelaxations evaluated with force-transducers are 58.4 % (n=6) and 57.5 % (n=6) respectively. Laser treatment slightly induces higher biophysical effects than High power LED-irradiation but lacking a significant difference. Therefore experiments demonstrate, that focussed high power LED treatment of vascular tissue is able to substitute arterial laser-treatments. Consequences in cardiophysiology are discussed. (author)