Adverse balance of nitric oxide/peroxynitrite in the dysfunctional endothelium can be reversed by statins

Vascular endothelial dysfunction is a complex phenomenon that might be caused by a deficiency of nitric oxide (NO) and an overproduction of peroxynitrite (ONOO-). This study used a nanotechnological approach to monitor the in vitro effect of statins on the [NO]/[ONOO-] balance in normal and dysfunctional endothelial cells. NO and ONOO- were measured by electrochemical nano-sensors in a single human umbilical vein endothelial cell (HUVEC) treated with atorvastatin or simvastatin for 24 hours in the presence or absence of 50 mu g/mL oxidized-LDL. An imbalance between [NO]/ [ONOO-] concentrations was used as an indicator of endothelial dysfunction and correlated with endothelial nitric oxide synthase (eNOS) expression. Ox-LDL induced dysfunction of the endothelium by uncoupling eNOS. NO concentration decreased from 300 12 to 146 +/- 8 nmol/L and ONOO- increased from 200 +/- 9 to 360 13 nmol/L. The [NO]/[ONOO-] balance decreased from 1.50 +/- 0.04 (control) to 0.40 +/- 0.03 for cells co-incubated with ox-LDL. Treatment with statins reversed eNOS uncoupling, induced by oxidized-LDL and significantly increased the [NO]/[ONOO-] balance to 1.2 +/- 0.1. These results demonstrate that statins can restore endothelial function by increasing eNOS expression, decreasing eNOS uncoupling, reducing the ONOO- level (nitroxidative stress), and shifting the [NO]/[ONOO-] balance towards NO.