Atorvastatin-induced cardioprotection is mediated by increasing inducible nitric oxide synthase and consequent S-nitrosylation of cyclooxygenase-2.
We determined the effects of cyclooxygenase-1 (COX-1; SC-560), COX-2 (SC-58125), and inducible nitric oxide synthase (iNOS; 1400W) inhibitors on atorvastatin (ATV)-induced myocardial protection and whether iNOS mediates the ATV-induced increases in COX-2. Sprague-Dawley rats received 10 mg ATV.kg(-1).day(-1) added to drinking water or water alone for 3 days and received intravenous SC-58125, SC-560, 1400W, or vehicle alone. Anesthesia was induced with ketamine and xylazine and maintained with isoflurane. Fifteen minutes after intravenous injection rats underwent 30-min myocardial ischemia followed by 4-h reperfusion [infarct size (IS) protocol], or the hearts were explanted for biochemical analysis and immunoblotting. Left ventricular weight and area at risk (AR) were comparable among groups. ATV reduced IS to 12.7% (SD 3.1) of AR, a reduction of 64% vs. 35.1% (SD 7.6) in the sham-treated group (P < 0.001). SC-58125 and 1400W attenuated the protective effect without affecting IS in the non-ATV-treated rats. ATV increased calcium-independent NOS (iNOS) [11.9 (SD 0.8) vs. 3.9 (SD 0.1) x 1,000 counts/min; P < 0.001] and COX-2 [46.7 (SD 1.1) vs. 6.5 (SD 1.4) pg/ml of 6-keto-PGF(1alpha); P < 0.001] activity. Both SC-58125 and 1400W attenuated this increase. SC-58125 did not affect iNOS activity, whereas 1400W blocked iNOS activity. COX-2 was S-nitrosylated in ATV-treated but not sham-treated rats or rats pretreated with 1400W. COX-2 immunoprecipitated with iNOS but not with endothelial nitric oxide synthase. We conclude that ATV reduced IS by increasing the activity of iNOS and COX-2, iNOS is upstream to COX-2, and iNOS activates COX-2 by S-nitrosylation. These results are consistent with the hypothesis that preconditioning effects are mediated via PG.
Atar
Shaul
S
Division of Cardiology, University of Texas Medical Branch, Galveston, TX 77555-0553, USA.
Ye
Yumei
Y
Lin
Yu
Y
Freeberg
Sheldon Y
SY
Nishi
Shawn P
SP
Rosanio
Salvatore
S
Huang
Ming-He
MH
Uretsky
Barry F
BF
Perez-Polo
Jose R
JR
Birnbaum
Yochai
Y
D000818:Animals; D000069059:Atorvastatin; D002316:Cardiotonic Agents / Q000008:administration & dosage; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000008:administration & dosage; D016861:Cyclooxygenase Inhibitors; D006321:Heart / Q000187:drug effects; D006538:Heptanoic Acids / Q000008:administration & dosage*; D019194:Ischemic Preconditioning / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011758:Pyrroles / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome
D002316:Cardiotonic Agents; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D006538:Heptanoic Acids; D011758:Pyrroles; D000069059:Atorvastatin; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat