Introduction: 

The mineralocorticoid hormone aldosterone is a mediator of the stiff endothelial cell syndrome (SECS), a hallmark for endothelial dysfunction and cardiovascular disease. SECS is characterized by an increase of epithelial sodium channels (ENaC) in the plasma membrane, which stiffens the cells and decreases nitric oxide (NO) release. Consequently, the mineralocorticoid receptor (MR) antagonist spironolactone is increasingly recognized as an effective treatment strategy particularly in the long-term. Here we present that spironolactone protects the endothelium due to positive long-term effects on ENaC expression, cell stiffness and NO release.

Methods: 

Human umbilical vein endothelial cells (HUVEC) were cultured over four weeks in the presence of aldosterone, treated or untreated with spironolactone. ENaC and MR expression were quantified by qRT-PCR. Surface abundance of ENaC was determined by quantum dot immunostaining. Mechanical stiffness of living in vitro and ex vivo endothelial cells was studied using atomic force microscopy. NO release was measured as nitrite in the supernatant of the culture media.

Results: 

Over time, spironolactone-untreated endothelium exerted an increase of (i) ENaC (32%) and MR (120%) mRNA levels, (ii) ENaC in the plasma membrane (43%), (iii) cortical stiffness of HUVEC (28%) and human endothelial cells of ex vivo arteries. (iv) NO production decreased (20%). Spironolactone treatment significantly reduced all these effects.

Conclusion: 

We postulate that SECS manifests itself over time finally leading to endothelial dysfunction. The fact that spironolactone prevents SECS explains the protective effects observed in patients with cardiovascular pathologies and emphasizes the drug's clinical usage explicitly for long-term medication.