Abstract 1568: Loss of Ischemic Postconditioning in the Mouse Hearts Lacking Adenosine A 1 or Bradykinin B 2 Receptors

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Lei Xi ◽  
Anindita Das ◽  
Zhi-Qing Zhao ◽  
Vanessa F Merino ◽  
Michael Bader ◽  
...  
Keyword(s):  
Infarct Size ◽  
G Protein ◽  
Contractile Function ◽  
Gene Knockout ◽  
Myocardial Infarct ◽  
Membrane Receptors ◽  
Ischemic Postconditioning ◽  
Myocardial Infarct Size ◽  
G Protein Coupled

Background: Ischemic postconditioning (PostC) is a recently described cardioprotective modality against reperfusion injury, through a series of brief episodes of reperfusion/ischemia at the very onset of reperfusion. It has been well recognized that PostC can activate cellular signaling cascade, in which the role of G protein-coupled membrane receptors serving as upstream triggers of PostC remains to be established. Hence the goal of this study was to determine a definitive role of adenosine A 1 receptors (A1) and bradykinin B 1 or B 2 receptors (B1 or B2) in PostC, using gene knockout (KO) mice. Methods & Results: The hearts isolated from adult male C57BL/6J wild-type mice (C57-WT) or A1, B1, or B2 KO mice (n=7–9 per group) were subjected to 20 min of zero-flow global ischemia and 30 min of reperfusion with or without PostC in a Langendorff isolated, buffer-perfused heart model. PostC, consisted of 6 cycles of 10 sec of reperfusion and 10 sec of ischemia, significantly reduced myocardial infarct size (22.8±3.1%, Mean±SEM) as compared with C57-WT controls (35.1±2.8%, P<0.05). As shown in Figure below, the infarct-limiting protection of PostC was absent in A1-KO (34.9±2.7%) or B2-KO (33.3±1.7%) and was partially attenuated in B1-KO (25.6±2.9%) mice, as compared with the corresponding non-PostC controls under same genetic background (P>0.05). However, cardiac contractile function and coronary flow at the end of reperfusion were not significantly altered by PostC. Conclusion: PostC-induced infarct size reduction in globally ischemic mouse hearts is triggered by activation of multiple G protein-coupled membrane receptors, which include A1, B2, and, to a lesser extent, B1 receptors.

Abstract P290: RhoA Protects Against Myocardial Ischemia/Reperfusion Injury

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Sunny Y Xiang ◽  
Shigeki Miyamoto ◽  
Davy Vanhoutte ◽  
Jeffery D Molkentin ◽  
Gerald W Dorn ◽  
...  
Keyword(s):  
Infarct Size ◽  
Contractile Function ◽  
Ex Vivo ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Small Gtpase ◽  
Myocardial Infarct Size ◽  
Rhoa Signaling

The small GTPase RhoA has established effects on cytoskeletal dynamics and gene expression but its role in regulating cardiac physiology and disease remains elusive. To characterize the in vivo role of RhoA signaling in cardiomyocytes, we generated conditional cardiac-specific RhoA transgenic mice (CA-RhoA) with 2–5 fold increases in RhoA activation in the adult heart. CA-RhoA mice show no overt cardiomyopathy but when challenged by in vivo or ex vivo I/R, these mice exhibit strikingly increased tolerance to injury. Compared to control mice, myocardial infarct size in CA-RhoA mice is reduced by 60–70% (20% vs. 50%, ex vivo; 10% vs. 37%, in vivo) and recovery of contractile function is significantly improved. Protein kinase D (PKD) is robustly activated in CA-RhoA hearts and inhibiting PKD reverses the cardioprotection afforded by RhoA. Both RhoA and PKD are also activated during I/R and blocking PKD augments I/R injury in WT mouse hearts. To further confirm that RhoA and PKD play a protective role during I/R, cardiac-specific RhoA knockout mice generated in the Molkentin laboratory were tested and demonstrated to show decreased tolerance to I/R injury, manifests as increased infarct size (42% vs. 23%) and lactate dehydrogenase release relative to control mice. This was accompanied by attenuated PKD activation during I/R. Taken together, our data indicates that RhoA signaling in adult cardiomyocytes promotes survival and reveals an unexpected role of PKD as a downstream mediator of RhoA and on cardioprotection against I/R.

scholarly journals Investigating the role of GSK3beta kinase as a molecular target for myocardial infarct size reduction by using novel pharmacological inhibitors

2013 ◽  
Vol 34 (suppl 1) ◽  
pp. 777-777
Author(s):  
I. Andreadou ◽  
A. Lazari ◽  
S. I. Bibli ◽  
N. Gaboriaud-Kolar ◽  
A. L. Skaltsounis ◽  
...  
Keyword(s):  
Infarct Size ◽  
Myocardial Infarct ◽  
Molecular Target ◽  
Size Reduction ◽  
Myocardial Infarct Size ◽  
Infarct Size Reduction

Abstract 2894: Essential Role of ERK 1/2 in Sildenafil-Induced Early and Delayed Cardioprotection in Mice

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Anindita das ◽  
Lei Xi ◽  
Fadi N Salloum ◽  
Yuan J Rao ◽  
Rakesh C Kukreja
Keyword(s):  
South Carolina ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Critical Role ◽  
Heart Association ◽  
Myocardial Infarct Size ◽  
Western Blots ◽  
Delayed Cardioprotection

Background: Sildenafil (SIL), a potent inhibitor of phosphodiesterase-5 induces powerful protection against myocardial ischemia-reperfusion (I-R) injury through activation of protein kinase G (PKG). However, the downstream targets of PKG in SIL-induced cardioprotection remain unclear. We hypothesized that PKG-dependent activation of survival kinase, ERK may play a critical role in SIL-induced cardioprotection in mice. Methods & Results: Ventricular myocytes were isolated from adult male ICR mice and exposed to 40 min of simulated ischemia (SI) with/without 1 hr pre-incubation of SIL (1 μM). Myocyte necrosis and apoptosis were determined after 1 hr or 18 hrs of reoxygenation (RO) using trypan blue or TUNEL assay, respectively. Pretreatment with SIL protected cardiomyocytes after SI-RO (necrosis 18.5±0.5% and apoptosis 6.6±0.7%; n=4, p<0.001) as compared with controls (necrosis 42.1±1.8% and apoptosis 23.3±0.9%). Co-incubation of PD98059 (20 μM), a selective ERK1/2 inhibitor blocked both anti-necrotic and anti-apoptotic protection in cardiomyocytes. Furthermore, intra-coronary infusion of SIL (1 μM) in Langendorff isolated mouse hearts 10 min prior to zero-flow global I (20 min) and R (30 min) significantly reduced myocardial infarct size (from 29.4±2.4% to 16.0±3.0%; p<0.05, n=6). Co-treatment of PD98059 abrogated SIL-induced protection (33.0±5.9; n=4). To evaluate the role of ERK1/2 in delayed cardioprotection, mice were treated with saline or SIL (0.7 mg/kg i.p.) 24 hours before global I-R in Langendorff mode. PD98059 (1 mg/kg) was administered (i.p.) 30 min before the treatment of SIL. Infarct size was reduced from 27.6±3.3% in saline-treated controls to 6.9±1.2% in SIL-treated mice (P<0.05, n=6). The delayed protective effect of SIL was also abolished by PD98059 (22.5±2.3%). Western Blots revealed that SIL significantly increased phosphorylation of ERK1/2 which was blocked by PKG inhibitor, KT5823 in the heart and adult myocytes. Selective knockdown of PKG in cardiomyocytes with short hairpin RNA of PKG also blocked the phosphorylation of ERK1/2. Conclusion: SIL-induced cardioprotection involves the activation and phosphorylation of ERK which appear to be intimately linked with a PKG-dependent survival pathway. This research has received full or partial funding support from the American Heart Association, AHA Mid-Atlantic Affiliate (Maryland, North Carolina, South Carolina, Virginia & Washington, DC).

Myocardial temperature in acute myocardial infarction: protection with mild regional hypothermia

1997 ◽  
Vol 273 (1) ◽  
pp. H220-H227 ◽  
Author(s):  
S. L. Hale ◽  
R. A. Kloner
Keyword(s):  
Infarct Size ◽  
Myocardial Infarct ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Control Group ◽  
Myocardial Infarct Size ◽  
Local Cooling ◽  
Risk Zone ◽  
Myocardial Temperature

This study tests the hypothesis that a 2-4 degrees C reduction in myocardial temperature, obtained by using topical regional hypothermia (TRH), reduces infarct size. Anesthetized rabbits received coronary artery occlusion and reperfusion. We cooled hearts in the TRH group by applying an ice bag directly over the risk zone; the control group received no intervention. Risk zone myocardial temperature (MT) in the TRH group was reduced at occlusion by 2 degrees C from baseline and after 5 min of occlusion by 3.6 degrees C. In the control group, MT in the risk region remained within 0.3 degree C of baseline. The ischemic area was similar in both groups, yet infarct size in the TRH group was reduced by an average of 65% compared with the control group. Infarct size closely correlated with MT in the risk region at the time of occlusion. In a second protocol in which all hearts were paced, infarct size was 21% of the risk region in TRH hearts compared with 44% in controls. These results strongly support the important role of MT in the progression of necrosis and demonstrate that the application of local cooling to the risk region profoundly reduces myocardial infarct size.

scholarly journals Loss of Protein Kinase Novel 1 (PKN1) is associated with mild systolic and diastolic contractile dysfunction, increased phospholamban Thr17 phosphorylation, and exacerbated ischaemia-reperfusion injury

2017 ◽  
Vol 114 (1) ◽  
pp. 138-157 ◽  
Author(s):  
Asvi A Francois ◽  
Kofo Obasanjo-Blackshire ◽  
James E Clark ◽  
Andrii Boguslavskyi ◽  
Mark R Holt ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Infarct Size ◽  
Cell Injury ◽  
Contractile Function ◽  
Myocardial Infarct ◽  
Neonatal Rat ◽  
Myocardial Infarct Size ◽  
Ischaemia Reperfusion ◽  
Sirna Knockdown

Abstract Aims PKN1 is a stress-responsive protein kinase acting downstream of small GTP-binding proteins of the Rho/Rac family. The aim was to determine its role in endogenous cardioprotection. Methods and results Hearts from PKN1 knockout (KO) or wild type (WT) littermate control mice were perfused in Langendorff mode and subjected to global ischaemia and reperfusion (I/R). Myocardial infarct size was doubled in PKN1 KO hearts compared to WT hearts. PKN1 was basally phosphorylated on the activation loop Thr778 PDK1 target site which was unchanged during I/R. However, phosphorylation of p42/p44-MAPK was decreased in KO hearts at baseline and during I/R. In cultured neonatal rat ventricular cardiomyocytes (NRVM) and NRVM transduced with kinase dead (KD) PKN1 K644R mutant subjected to simulated ischaemia/reperfusion (sI/R), PhosTag® gel analysis showed net dephosphorylation of PKN1 during sI and early R despite Thr778 phosphorylation. siRNA knockdown of PKN1 in NRVM significantly decreased cell survival and increased cell injury by sI/R which was reversed by WT- or KD-PKN1 expression. Confocal immunofluorescence analysis of PKN1 in NRVM showed increased localization to the sarcoplasmic reticulum (SR) during sI. GC-MS/MS and immunoblot analysis of PKN1 immunoprecipitates following sI/R confirmed interaction with CamKIIδ. Co-translocation of PKN1 and CamKIIδ to the SR/membrane fraction during sI correlated with phospholamban (PLB) Thr17 phosphorylation. siRNA knockdown of PKN1 in NRVM resulted in increased basal CamKIIδ activation and increased PLB Thr17 phosphorylation only during sI. In vivo PLB Thr17 phosphorylation, Sarco-Endoplasmic Reticulum Ca2+ ATPase (SERCA2) expression and Junctophilin-2 (Jph2) expression were also basally increased in PKN1 KO hearts. Furthermore, in vivo P-V loop analysis of the beat-to-beat relationship between rate of LV pressure development or relaxation and end diastolic P (EDP) showed mild but significant systolic and diastolic dysfunction with preserved ejection fraction in PKN1 KO hearts. Conclusion Loss of PKN1 in vivo significantly reduces endogenous cardioprotection and increases myocardial infarct size following I/R injury. Cardioprotection by PKN1 is associated with reduced CamKIIδ-dependent PLB Thr17 phosphorylation at the SR and therefore may stabilize the coupling of SR Ca2+ handling and contractile function, independent of its kinase activity.

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