Background-A potential mechanism for left ventricular (LV) remodeling after myocardial infarction (MI) is activation of the matrix metalloproteinases (MMPs). This study examined the effects of MMP inhibition (MMPi) on regional LV geometry and MMP levels after MI. Methods and Results-In pigs instrumented with radiopaque markers to measure regional myocardial geometry, MI was created by ligating the obtuse marginals of the circumflex artery. In the first study, pigs were randomized to MMPi (nϭ7; PD166793, 20 mg · kg Ϫ1 · d Ϫ1 ) or MI only (nϭ7) at 5 days after MI, and measurements were performed at 2 weeks. Regional MI areas were equivalent at randomization and were increased in the MI-only group at 2 weeks after MI compared with the MMPi group. In the second study, pigs randomized to MMPi (nϭ9) or MI only (nϭ8) were serially followed up for 8 weeks. At 8 weeks after MI, LV end-diastolic dimension was lower with MMPi than in the MI-only group (4.7Ϯ0.1 versus 5.1Ϯ0.1 cm, PϽ0.05). Regional MI area was reduced with MMPi at 8 weeks after MI (1.3Ϯ0.1 versus 1.7Ϯ0.1 cm 2 , PϽ0.05). MMPi reduced ex vivo MMP proteolytic activity. In the MI region, membrane-type MMP levels were normalized and levels of the endogenous tissue inhibitor of MMPs (TIMP-1) were increased compared with normal levels with MMPi. These effects were not observed in the MI-only group. Conclusions-MMPi

Background-Induction of matrix metalloproteinases (MMPs) contributes to adverse remodeling after myocardial infarction (MI). Whether a region-and type-specific distribution of MMPs occurs within the post-MI myocardium remained unknown. Methods and Results-Ten sheep were instrumented with a sonomicrometry array to measure dimensions in 7 distinct regions corresponding to the remote, transition, and MI regions. Eight sheep served as reference controls. The relative abundance of representative MMP types and the tissue inhibitors of the MMPs (TIMPs) was quantified by immunoblotting. Segment length increased from baseline in the remote (24.9Ϯ5.4%), transition (18.0Ϯ2.9%), and MI (53.8Ϯ11.0%) regions at 8 weeks after MI (PϽ0.05) and was greatest in the MI region (PϽ0.05). Region-and type-specific changes in MMPs occurred after MI. For example, MMP-1 and MMP-9 abundance was unchanged in the remote, fell to 3Ϯ2% in the transition, and was undetectable in the MI region (PϽ0.05). MMP-13, MMP-8, and MT1-MMP increased by Ͼ300% in the transition and MI regions (PϽ0.05). TIMP abundance decreased significantly in the transition region after MI and fell to undetectable levels within the MI region. Conclusions-The unique findings of this study were 2-fold. First, changes in regional geometry after MI were associated with changes in MMP levels. Second, a region-specific portfolio of MMPs was induced after MI and was accompanied by a decline in TIMP levels, indicative of a loss of MMP inhibitory control. Targeting the regional imbalance between specific MMPs and TIMPs within the post-MI myocardium holds therapeutic potential.

Rationale: Although premenopausal females have a lower risk for cardiovascular disease, the mechanism(s) are poorly understood. Objective: We tested the hypothesis that cardioprotection in females is mediated by altered mitochondrial protein levels and/or posttranslational modifications. Methods and Results: Using both an in vivo and an isolated heart model of ischemia and reperfusion (I/R), we found that females had less injury than males. Using proteomic methods we found that female hearts had increased phosphorylation and activity of aldehyde dehydrogenase (ALDH)2, an enzyme that detoxifies reactive oxygen species (ROS)-generated aldehyde adducts, and that an activator of ALDH2 reduced I/R injury in males but had no significant effect in females. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, blocked the protection and the increased phosphorylation of ALDH2 in females, but had no effect in males. Furthermore, we found an increase in phosphorylation of ␣-ketoglutarate dehydrogenase (␣KGDH) in female hearts. ␣KGDH is a major source of ROS generation particularly with a high NADH/NAD ratio which occurs during I/R. We found decreased ROS generation in permeabilized female mitochondria given ␣KGDH substrates and NADH, suggesting that increased phosphorylation of ␣KGDH might reduce ROS generation by ␣KGDH. In support of this hypothesis, we found that protein kinase C-dependent phosphorylation of purified ␣KGDH reduced ROS generation. Additionally, myocytes from female hearts had less ROS generation following I/R than males and addition of wortmannin increased ROS generation in females to the same levels as in males. Conclusions: These data suggest that posttranslational modifications can modify ROS handling and play an important role in female cardioprotection. (Circ Res. 2010;106:1681-1691.)Key Words: gender difference Ⅲ cardioprotection Ⅲ mitochondria Ⅲ proteomics Ⅲ aldehyde dehydrogenase M any epidemiological studies have demonstrated that premenopausal women have a reduced risk of cardiovascular disease compared to their male counterparts 1 and that in postmenopausal women the risk reaches or even exceed the rates for men. In contrast, 2 large prospective clinical trials, the Heart and Estrogen-Progestin Replacement Study and Women's Health Initiative (WHI), failed to show reduced cardiac events in post menopausal women on hormone replacement therapy. Possible reasons for the discrepancy are discussed elsewhere. 2 The lack of protection in the WHI also contrasts with protection that is observed in a number of animal studies in which estrogen has been shown to be protective. [3][4][5][6][7][8][9][10][11][12][13][14] To understand why hormone replacement therapy was not protective in the WHI, it is important to understand the mechanism by which estrogen mediates protection.The effects of estrogen are usually attributed to estrogen binding to estrogen receptors (ERs) ␣ or ␤, which are nuclear receptors that act as ligand gated transcription factors. Estrogen binding to ERs has been shown to alter gene...