Endothelial function: cardiovascular disease and erectile dysfunction
The endothelium is a thin layer of specialized cells that lines the lumen of arteries and veins. It is a real organ that regulates numerous functions including:
- Semipermeable barrier, to regulate the passage of substances from the blood to extracellular fluids and vice versa
- Angiogenesis and vascular remodelling, i.e. formation of new capillaries and compensation circles
- Fluidity of the blood, through the regulation of coagulation, fibrinolysis and aggregation of platelets
- Inflammation, regulating the adhesion and activation of circulating leukocytes
- Oxidation of lipoproteins and their deposition in the wall of the vessels
When one or more of these functions is compromised we speak about endothelial dysfunction, a pathological condition that affects all organs but with more evident consequences on cardiac health and, in men, on erectile function.
Endothelial dysfunction is the most important factor in the development of atherosclerosis, that is, the narrowing of the cardiac arteries by intramural lipid deposition. Endothelial anomalies in fact cause inflammatory phenomena with adhesion of leukocytes and activation of inflammation and oxidation of circulating lipoproteins that overcome the endothelial barrier and form accumulations. The presence of dyslipidaemia (increase of cholesterol and LDL) accelerates this process and the most used treatment is precisely the reduction of cholesterol, for example with statins. However, individuals with very low circulating lipids can still develop atherosclerosis if endothelial inflammation is present as well as increased lipids do not cause deposits if inflammation is not present. In summary, the ideal treatment of atherosclerosis and ischemic heart disease is the correction of endothelial dysfunction.
H2S, in concert with nitric oxide (NO) and carbon monoxide (CO), is one of the main players in vasodilation and neo-angiogenesis and is also involved in the regulation of coagulation and platelet activation. All these activities indicate a primary role of H2S deficiency in endothelial dysfunction. In fact, experimental data confirm the potential benefit of H2S support strategies in atherosclerosis, and in cardiovascular diseases.
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Erectile dysfunction is the inability to obtain and / or maintain a penile erection sufficient to complete satisfactory sexual intercourse. The release of H2S by the endothelium and perivascular muscle cells of the corpora cavernosa is essential for correct erectile function. It cooperates with nitric oxide (NO) in inducing and maintaining the erection following sexual arousal and may even compensate a relative deficit of NO. In experimental models the delivery of H2S efficiently corrects erectile dysfunction. H2S is also an inhibitor of PDE5 and ay sinergize with the drugs commonly used for the disease. Treatments for erectile dysfunction based on a support to H2S have been proposed as a complementation or substitution to PDE5 inhibitors (e.g. sildenafil) but no H2S-supporting drugs for human use were available so far.
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