Blood irradiation by He-Ne laser induces a decrease in platelet responses to physiological agonists and an increase in platelet cyclic GMP

Abstract

The effect of He-Ne laser irradiation on platelet adhesion, activation and aggregation was investigated. Citrated whole blood was irradiated in vitro by He-Ne laser (632.8 nm, 7 mW) and then subjected to shear stress (1300 s-1) on subendothelial extracellular matrix (ECM)-coated plates. Laser irradiation was followed by a decrease in platelet adhesion and aggregation on ECM under flow conditions in a time exposure-dependent manner (by 30-40%). The inhibiting effect of laser light on platelets was detectable up to 1 h after the termination of irradiation. Laser irradiation of either platelet-rich plasma, gel-filtered platelets, platelet-poor plasma, or packed blood cells followed by whole blood reconstitution revealed a marked decrease in platelet deposition on ECM only in the cases of platelet-rich plasma or gel filtered platelets. In conventional aggregometry, laser-treated platelet-rich plasma demonstrated a diminished platelet response to both thrombin receptor-activating peptide (TRAP), converting a two-wave aggregation curve to reversible, and to the protein kinase C activator PMA (by 45%). In flow cytometry analysis, irradiated platelets presented lower fibrinogen binding and P-selectin expression in response to TRAP. Laser irradiation had no additional inhibitory effect on dibutyryl cGMP- and dibutyryl cAMP-pretreated platelets. A 50% increase in cGMP level was observed in laser-treated gel filtered platelets, both in the presence and in absence of the phosphodiesterase inhibitor, isobuthylmethylxanthine. The results suggest that guanylate cyclase is one of the primary mediators of the laser effect on platelet function.

Low‐Level Laser Irradiation Exerts Antiaggregative Effect on Human Platelets Independently on the Nitric Oxide Metabolism and Release of Platelet Activation Markers

“…On the other hand, Mohan et al [ 5 ] noted decreased platelet responsiveness following the LLLT. Similar results were observed by Eldar et al [ 6 ] and Brill et al [ 7 ].…”

“…Noteworthy, we are the first to demonstrate that the antiplatelet effect of low-energy laser radiation also applies to the whole blood preparations. The studies published up to date [ 4 – 7 ] were conducted on platelet-rich plasma (PRP). Brill et al [ 7 ] showed reduced activity of platelet aggregation following LLLT ( λ = 632.8 nm and energy of 0.4–4.2 J) when measured in a classical optical aggregometer in response to TRAP.…”

“…Several factors are postulated to modify platelet activity and inflammatory response, among which nitric oxide (NO) is one of the best known [ 2 – 7 ]. The low-energy laser irradiation exposure increases the production of NO in some experimental models conducted in vitro and in vivo [ 8 , 9 ].…”

Effect of the transdermal low-level laser therapy on endothelial function

“…In study by Brill et al the effect of LLLT was varying dependent on the wave length and the HeNe laser with the λ = 632 nm and power of 7 mW was associated with decreased platelet aggregation induced by TRAP (the thrombine receptor agonist peptide) [34, 35]. The effect was also explained by changes in the nitric oxide metabolism, as assessed by cGMP levels.…”

Enhancement of Human Blood Storage Period by Irradiation of Low Level He-Ne Laser

“…The most used laser of low level laser studies are He-Ne laser emitting light at a wavelength of 632.8 nm [21]- [26]. There is a fact that low powered He-Ne laser irradiation produced a protective effect on RBC membranes, reducing hypotonic hemolysis and stabilizing the cell membrane [27].…”