Background/Objectives: Sulodexide (SDX) is a drug known for restoring the glycocalyx, thereby offering endothelial protection and regulating permeability. Additionally, it has antithrombotic and anti-inflammatory properties and has shown arterial vasodilatory effects. Endothelial cells play a crucial role in maintaining homeostasis, with their dysfunction being a key contributor to loss in vasodilatory response, especially in arterial pathologies. The aim of this study was to investigate the effects of SDX on stimulated vascular tonus in human arterial samples and to assess the function of the endothelial layer as a source of nitric oxide (NO). Methods: A total of 16 internal mammary artery remnants from coronary artery bypass graft surgeries were dissected into endothelium-intact and endothelium-denuded groups (n = 8 each). The arterial rings were equilibrated under tension, with their basal tonus recorded before and after phenylephrine stimulation. SDX’s impact on arterial contraction was assessed through cumulative dose–response curves. NO synthase inhibitor (Nω-nitro-L-arginine methyl ester) was used to assess SDX’s vasodilatory effect over the NO pathway. Results: SDX application resulted in concentration-dependent vasorelaxation in both endothelium-intact and endothelium-denuded groups at certain doses. However, the inhibitory effect of SDX was more pronounced in endothelium-intact rings at higher doses compared to endothelium-denuded rings (p < 0.05). Similar inhibition of contraction curves was achieved for both endothelium-intact and endothelium-denuded rings after L-NAME pre-incubation, suggesting a necessity for NO-related endothelial pathways. Conclusions: SDX exerts a concentration-dependent inhibition on arterial contraction, emphasizing the critical role of an intact endothelium and NO-mediated pathways in this process. This underscores SDX’s potential in treating endothelial dysfunction-related pathologies.

Chronic venous disease (CVD) is a proqgressive and underestimated condition related to a vicious circle established by venous reflux and endothelial inflammation, leading to vein dilation and histology distortion, including loss of media tone. Sulodexide (SDX) is a drug restoring the glycocalyx that demonstrated endothelial protection and permeability regulation, together with anti-thrombotic and anti-inflammatory roles. In the lab it also exhibited vein contractility function. The aim of the present study was to show the possible role of endothelium and nitric oxide pathway on SDX’s veno-contractile effect on human saphenous veins. The remnants of great saphenous vein (GSV) segments (n = 14) were harvested during coronary artery bypass graft surgery. They were dissected as endothelium-intact (n = 8) and denuded rings (n = 6). First, a viability test was carried out in bath with Krebs–Henseleit solution to investigate a control and basal tension value. After this, cumulative doses of SDX were applied to rings and contraction values were studied in endothelium-intact phenylephrine (PheE, 6 × 10⁻⁷ M) pre-contracted vein rings. Finally, endothelium-intact PheE pre-contacted vein rings were treated by nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 10⁻⁴ M) for 10 min. Contraction protocol was applied, and contraction values were measured in cumulative doses of SDX. The same protocol was applied to endothelium-denuded vein rings to investigate the effect of SDX. Saphenous vein rings showed an increase in contraction to cumulative doses of SDX. In endothel-intact rings, KCL-induced contraction from 92.6% ± 0.3 to 112.9% ± 0.4 with cumulative SDX doses. However, SDX did not show any veno-contractile effect on endothel-denuded rings. In denuded rings contraction responses measured from 94.9% ± 0.3 to 85.2% ± 0.3 with increasing doses of SDX, indicating no significant change. Nitric oxide synthase inhibitor (L-NAME) prohibited the contraction response of the sulodexide in all dosages, indicating that the contractile function of SDX was mediated by endothelial derived nitric oxide. Results of endothel-intact and denuded rings with L-NAME showed a similar incline with denuded rings with SDX only. The results confirmed SDX’s veno-contractile effect in human samples, by means of nitric oxide synthase pathways involvement.

Background/Objectives: Body Protection Compound-157 (BPC 157) is a stable gastric pentadecapeptide with cytoprotective, pro-angiogenic, and nitric oxide (NO)-modulating properties that has gained increasing attention for its therapeutic potential. Although vasodilatory effects have been demonstrated in animal models, functional evidence in human arterial tissue remains limited. This study investigated the effects of BPC 157 on vascular tone in human internal mammary artery (IMA) rings and evaluated the contribution of endothelial NO signaling. Methods: Residual IMA segments obtained from elective coronary artery bypass graft surgeries (n = 12) were dissected into endothelium-intact and endothelium-denuded rings. Following equilibration, the rings were challenged by phenylephrine (PheE; 3 × 10⁻⁶ M) to induce contraction. Cumulative concentration–response curves of BPC 157 (0.01–1 mg/mL) for five consecutive doses were constructed. The involvement of NO was assessed by BPC 157 dose–response curves in the nitric oxide synthase (NOS) inhibitor Nω-nitro-L-arginine methyl ester (L-NAME; 10⁻⁶ M) pre-incubated rings. Maximum force of contraction, area under the curve, maximum response (Emax), and negative logarithm of the half-maximal effective concentration (pEC50) values were analyzed. Results: BPC 157 produced a concentration-dependent reduction in PheE-induced contraction in both groups, with significantly greater relaxation in endothelium-intact rings (p < 0.05). L-NAME increased contractile responsiveness in intact rings and attenuated BPC 157-induced relaxation. Under NOS inhibition, differences between groups progressively diminished and concentration–response curves converged at higher concentrations. Emax analysis demonstrated that endothelial integrity markedly enhanced maximal vasorelaxation, whereas this advantage was largely abolished after NOS inhibition. Conclusions: BPC 157 induces concentration-dependent vasorelaxation in human arterial tissue, predominantly mediated via an endothelium-dependent NO pathway. Endothelial integrity primarily enhances maximal efficacy, while residual effects indicate additional mechanisms. These findings provide early mechanistic evidence for the vascular activity of BPC 157, although further molecular and in vivo studies are required to clarify its clinical relevance.