Role of iNOS and peroxynitrite-matrix metalloproteinase-2 signaling in myocardial late preconditioning in rats

Am J Physiol Heart Circ Physiol. 2010 Aug;299(2):H512-8. doi: 10.1152/ajpheart.00052.2010. Epub 2010 Jun 11.


We have previously shown that the inhibition of myocardial nitric oxide (NO) and peroxynitrite-matrix metalloproteinase (MMP) signaling by early preconditioning (PC) is involved in its cardioprotective effect. Therefore, in the present study, we investigated the role of NO and peroxynitrite-MMP signaling in the development of late PC. PC was performed by five consecutive cycles of 4-min coronary occlusion and 4-min reperfusion in anesthetized rats in vivo. Twenty-four hours later, hearts were subjected to a 30-min coronary occlusion followed by 180-min reperfusion to measure infarct size. In separate experiments, heart tissue was sampled to measure biochemical parameters before and 3, 6, 12, or 24 h after the PC protocol, respectively. Late PC decreased infarct size, increased cardiac inducible NO synthase (iNOS) activity and gene expression, and decreased SOD activity at 24 h significantly compared with sham-operated controls. Late PC increased cardiac superoxide levels significantly at 24 h; however, it did not change cardiac NO levels. Cardiac peroxynitrite levels were significantly decreased. Downstream cellular targets of peroxynitrite, MMP-2 and MMP-9 activities were decreased in the late PC group at 24 h compared with the sham-operated group. To verify if PC-induced inhibition of MMPs had a causative role in the reduction of infarct size, in separate experiments, we measured infarct size after the pharmacological inhibition of MMPs by ilomastat and found a significant reduction of infarct size compared with the vehicle-treated group. In conclusion, this is the first demonstration that the inhibition of cardiac peroxynitrite-MMP signaling contributes to cardioprotection by late PC and that pharmacological inhibition of MMPs is able to reduce infarct size in vivo. Furthermore, increased expression of iNOS may play a role in the development of late PC; however, increased iNOS activity does not lead to increased NO production in late PC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Enzyme Activation
  • Hydroxamic Acids
  • Indoles / pharmacology
  • Ischemic Preconditioning, Myocardial / methods*
  • Male
  • Matrix Metalloproteinase 2 / metabolism*
  • Matrix Metalloproteinase 9 / metabolism
  • Matrix Metalloproteinase Inhibitors
  • Myocardial Infarction / enzymology
  • Myocardial Infarction / pathology
  • Myocardial Infarction / prevention & control*
  • Myocardial Reperfusion Injury / enzymology
  • Myocardial Reperfusion Injury / pathology
  • Myocardial Reperfusion Injury / prevention & control*
  • Myocardium / enzymology*
  • Myocardium / pathology
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism*
  • Peroxynitrous Acid / metabolism*
  • Protease Inhibitors / pharmacology
  • Rats
  • Rats, Wistar
  • Signal Transduction* / drug effects
  • Superoxide Dismutase / metabolism
  • Superoxides / metabolism
  • Time Factors
  • Up-Regulation


  • Hydroxamic Acids
  • Indoles
  • Matrix Metalloproteinase Inhibitors
  • Protease Inhibitors
  • Superoxides
  • Peroxynitrous Acid
  • Nitric Oxide
  • Nitric Oxide Synthase Type II
  • Nos2 protein, rat
  • Superoxide Dismutase
  • Matrix Metalloproteinase 2
  • Mmp2 protein, rat
  • Matrix Metalloproteinase 9
  • ilomastat