Enhancement of laser-induced vasodilation by medicinal plants: The eNOS-dependent and antioxidant actions of Panax ginseng and Angelica keiskei.

Photobiomodulation (PBM) is a promising non-pharmacological approach to improve vascular function via nitric oxide (NO)-mediated pathways. However, its effectiveness can be limited under conditions of endothelial dysfunction. This study investigated whether Panax ginseng and Angelica keiskei, two medicinal plants known for their antioxidant and vasorelaxant properties, can enhance PBM-induced vasodilation through mechanisms involving endothelial nitric oxide synthase (eNOS). Aortic rings from Wistar rats were treated with increasing doses of a standardized plant extract combination and exposed to 660 nm laser irradiation. Optimal doses (50-200 mg/kg) significantly potentiated PBM-induced vasodilation, an effect abolished by pharmacological inhibition of NO signaling and endothelium removal. In a chronic eNOS inhibition model (L-NAME), the plant combination did not restore PBM effects but partially recovered acetylcholine-induced vasorelaxation, suggesting endothelial compensation. In mesenteric arteries, the herbal treatment improved acetylcholine sensitivity but did not alter flow-induced or laser-induced vasodilation, especially under hypertensive conditions. These findings highlight a synergistic interaction between phytotherapy and PBM, mediated primarily by eNOS activation and redox modulation, with potential translational relevance for vascular disorders.