During bacterial-endotoxemia endothelial damage and vascular smooth muscle dysfunction are observed. Large amounts of NO are released by iNOS and eNOS leading to vasodilatation and hypotension. Protein phosphatase 2B (calcineurin) activates eNOS by dephosphorylation and induces iNOS in macrophages, vascular smooth muscle cells and neutrophil granulocytes. We therefore hypothesized that the calcineurin inhibitor, Cyclosporin A (CsA) counteracts the lipopolysaccharide (LPS)-induced suppression of vasoreactivity. Mouse aortic rings were incubated with LPS (50 mg/mL, E. Coli 055:B5) or vehicle for 18h, at 37C and the effect of 2*10^-7 mol/L phenylephrine was recorded with a myograph. LPS exposure reduced contractility significantly in wild type and eNOS -/- mice whereas incubation with LPS and L-NAME (10^-4 mol/L) had no significant effect compared to vehicle. Removal of the endothelium in rings from wt mice before incubation with LPS and L-NAME (10^-4 mol/L) had no significant effect compared to vehicle whereas incubation with LPS alone significantly reduced contractility in rings without LPS. CsA 10^-6 M and 10^-7 M had no significant effect on vasoreactivity after LPS incubation but vasoreactivity were significantly improved after incubation with LPS and CsA 10^-5 M compared to rings incubated with LPS alone. We conclude that the LPS depressed vascular function is mediated by NO independent of the endothelium and eNOS in a murine in vitro model of LPS endotoxemia. Furthermore we conclude that the calcineurin inhibitor, Cyclosporin A, can improve vasoreactivity significantly after LPS incubation compared to vessels incubated with LPS alone.