Submitted on November 18, 2007
Accepted on May 6, 2008
The role of eNOS, iNOS and NF
B in upregulation and activation of cyclooxygenase-2 and infarct size reduction by atorvastatin
Yumei Ye1, Juan D Martinez2, J. Regino Perez-Polo3, Yu Lin4, Barry F Uretsky2, and Yochai Birnbaum1*
1 Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States; Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States
2 Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States
3 Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States
4 Galveston, Texas, United States; Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States
* To whom correspondence should be addressed. E-mail: yobirnba{at}utmb.edu.
Objectives: Pretreatment with atorvastatin (ATV) reduces infarct size (IS) and increases myocardial expression of phosphorylated endothelial nitric oxide synthase (P-eNOS), inducible NOS (iNOS), and cycloxygenase-2 (COX2) in the rat. Inhibiting COX2 abolished the ATV-induced IS limitation without affecting P-eNOS and iNOS expression. We investigated: 1) whether 3-day ATV pretreatment limits IS in eNOS-/- and iNOS-/- mouse; 2) whether COX2 expression and/or activation by ATV is eNOS-, iNOS and/or NF
B-dependent. Methods: Male C57BL/6 wild-type (WT), University of North Carolina eNOS-/-, and iNOS-/- mice received ATV 10 mg/kg/d (ATV+) or water alone (ATV-) for 3 days. Mice underwent 30min coronary artery occlusion and 4h of reperfusion, or hearts were harvested and subjected to ELISA, immunoblotting, biotin switch and electrophoretic mobility shift assay (EMSA). Results: ATV reduced IS only in the WT mice. ATV increased eNOS, P-eNOS, iNOS and COX2 levels, and activated NFB in WT mice. It also increased myocardial COX2 activity. In eNOS-/- mice, ATV increased COX2 expression, but not COX2 activity or iNOS expression. NFB was not activated by ATV in the eNOS-/- mice. In the iNOS-/- mice eNOS and P-eNOS levels were increased, but not iNOS and COX2 levels; however, NFB was activated. Conclusions: Both eNOS and iNOS are essential for the IS-limiting effect of ATV. Expression of COX2 by ATV is iNOS- but not eNOS- or NFB dependent. Activation of COX2 is dependent on iNOS.
