Abstract
BackgroundThe efficacy of Phosphodiesterase 5 (PDE5) inhibitors to re-establish endothelial function is reduced in diabetic patients. Recent evidences suggest that therapy with PDE5 inhibitors, i.e. sildenafil, may increase the expression of nitric oxide synthase (NOS) proteins in the heart and cardiomyocytes. In this study we analyzed the effect of sildenafil on endothelial cells in insulin resistance conditions in vitro.Methodology/Principal FindingsHuman umbilical vein endothelial cells (HUVECs) were treated with insulin in presence of glucose 30 mM (HG) and glucosamine 10 mM (Gluc-N) with or without sildenafil. Insulin increased the expression of PDE5 and eNOS mRNA assayed by Real time-PCR. Cytofluorimetric analysis showed that sildenafil significantly increased NO production in basal condition. This effect was partially inhibited by the PI3K inhibitor LY 294002 and completely inhibited by the NOS inhibitor L-NAME. Akt-1 and eNOS activation was reduced in conditions mimicking insulin resistance and completely restored by sildenafil treatment. Conversely sildenafil treatment can counteract this noxious effect by increasing NO production through eNOS activation and reducing oxidative stress induced by hyperglycaemia and glucosamine.Conclusions/SignificanceThese data indicate that sildenafil might improve NOS activity of endothelial cells in insulin resistance conditions and suggest the potential therapeutic use of sildenafil for improving vascular function in diabetic patients.
Highlights
Nitric oxide (NO) is a reactive free radical gas acting as an intracellular or extracellular messenger
Since several reports have shown that endothelial dysfunction is associated with insulin resistance [22,23,24], the aim of the present study was to investigate the role of sildenafil in NO production and changes in insulin signaling in Human umbilical vein endothelial cells (HUVECs) in basal and insulin resistance conditions
Phosphodiesterase 5 (PDE5) expression in HUVECs PDE-5 mRNA expression, measured in HUVECs cell line by reverse transcription (RT)-PCR, was detectable compared to the expression in human foetal corpora cavernosa cells used as positive control (Fig. 1A)
Summary
Nitric oxide (NO) is a reactive free radical gas acting as an intracellular or extracellular messenger. It is synthesized from Larginine by a family of isoforms of NO synthases (NOS 1–3). NO generation by NOS-3 (eNOS) in endothelial cells explains the effects of endothelial-dependent vasodilators on vascular relaxation and decreased platelet adhesion and aggregation. These and others effects of NO are mediated by increased cyclic GMP (cGMP) formation due to soluble guanylyl cyclase activation. Recent evidences suggest that therapy with PDE5 inhibitors, i.e. sildenafil, may increase the expression of nitric oxide synthase (NOS) proteins in the heart and cardiomyocytes. In this study we analyzed the effect of sildenafil on endothelial cells in insulin resistance conditions in vitro
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
