Simvastatin decreases nitric oxide overproduction and reverts the impaired vascular responsiveness induced by endotoxic shock in rats.

Abstract

Lipopolysaccharides (LPS) can be used to induce experimental endotoxic shock, which is characterized by a significant decrease in mean arterial pressure (MAP) and a decreased vasoconstrictor response that have been attributed to excessive nitric oxide production. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), in addition to lowering serum cholesterol levels, exert many pleiotropic effects, including anti-inflammatory action. In the present study, we investigated the effect of simvastatin, an HMG-CoA reductase inhibitor, on the production of nitric oxide and the cardiovascular response to LPS. Male Wistar rats were pretreated with different doses of simvastatin (10, 20, 40, and 80 mg/kg, i.p.) or saline 20 min before i.v. injection of LPS (1.5 mg/kg) or saline (control). MAP was continuously recorded and nitrate plasma concentration was determined during the 6-h experimental session at 1-h intervals. The pressor response to phenylephrine (1 microg/kg) was evaluated before and 6 h after LPS administration. In the LPS-treated group, there was a time-dependent increase in nitrate plasma concentration (P<0.001), and this response was decreased in simvastatin pretreated rats (P<0.001). We also observed that LPS decreased the pressor response to phenylephrine (P<0.001), an effect that was reverted by simvastatin pretreatment (P<0.05). However, simvastatin did not modify the decrease of MAP induced by LPS. We concluded that simvastatin decreases nitrate plasma concentration in response to LPS and recovers vascular responsiveness during an experimental endotoxic shock. These data suggest the potential use of HMG-CoA reductase inhibitors as a coadjuvant in the treatment of septic shock.