Propofol induces endothelial nitric oxide synthase phosphorylation and activation in human umbilical vein endothelial cells by inhibiting protein kinase C delta expression.

BACKGROUND AND OBJECTIVE

Protein kinase Cs (PKCs) are involved in the regulation of endothelial nitric oxide synthase (eNOS). The purpose of this study is to evaluate the role of PKC delta in mediating the effects of chronic treatment with propofol on eNOS activation in human umbilical venous endothelial cells.

METHODS

Human umbilical venous endothelial cells were treated chronically with propofol (1-100 micromol l(-1)) to induce phosphorylation of eNOS activation, which was assessed by immunoblot and cyclic GMP accumulation assay. The involvement of the phosphoinositide 3-kinase/Akt pathway was examined by an immunoblot assay. In addition, the role of PKC delta in regulating propofol-induced activation of eNOS was explored. Finally, cells were treated with a combination of ceramide (10 nmol l(-1)) and propofol (50 micromol l(-1)), and the role of protein phosphatase 2A in mediating drug-induced eNOS activation was evaluated.

RESULTS

Cells treated with propofol showed an increase in phosphorylation of eNOS at serine(1177) in a dose-dependent manner. Cyclic GMP accumulation was also increased accordingly. Akt was not phosphorylated in response to propofol (50 micromol l(-1)) at serine(473). In addition, a phosphoinositide 3-kinase inhibitor, LY294002 (10 micromol l(-1)), did not affect eNOS phosphorylation and nitric oxide production by propofol. Chronic treatment with propofol induced a downregulation of PKC delta, which was associated with eNOS activation. Moreover, ceramide inhibited the effect of propofol on eNOS activation.

CONCLUSION

Propofol induces eNOS activation through a PKC delta inhibition-dependent, protein phosphatase 2A-coordinated, but phosphoinositide 3-kinase/Akt-independent pathway.