PKA-mediated eNOS phosphorylation in the protection of ischemic preconditioning against no-reflow.

Abstract

OBJECTIVE:

To investigate whether ischemic preconditioning (IP) can reduce myocardial no-reflow by activating endothelial (e-) nitric oxide synthase (NOS) via the protein kinase A (PKA) pathway.

METHODS AND RESULTS:

In a 90-min ischemia and 3-h reperfusion model, minipigs were assigned into sham, ischemia-reperfusion (IR), IR+IP, IR+IP+L-NNA (an eNOS inhibitor, 10mg·kg(-1)), IR+IP+H-89 (a PKA inhibitor, 1.0μg·kg(-1)·min(-1)), IR+L-NNA, and IR+H-89 groups. IP pretreatment improved cardiac function and coronary blood flow, decreased the activities of creatine kinase by 36.6% after 90 min of ischemia and by 32.8% after 3 h of reperfusion (P<0.05), reduced the no-reflow areas from 49.9% to 11.0% (P<0.01), and attenuated the infarct size from 78.2% to 35.4% (P<0.01). IP stimulated myocardial PKA activities and the expression of PKA and Ser(133) phosphorylated (p-) cAMP response element-binding protein (CREB) in the reflow and no-reflow myocardium, and enhanced the activities of constitutive NOS and the phosphorylation of eNOS at Ser(1179) and Ser(635) in the no-reflow myocardium. IP suppressed the expression of tumor necrosis factor-α and P-selectin, and attenuated cardiomyocytes apoptosis by regulating the expression of Bcl-2 and caspase-3 in the reflow and no-reflow myocardium. The eNOS inhibitor L-NNA completely canceled these beneficial effects of IP without any influence on PKA activity, whereas the PKA inhibitor H-89 partially blocked the IP cardioprotective effects and eNOS phosphorylation at the same time.

CONCLUSION:

IP attenuates myocardial no-reflow and infarction after ischemia and reperfusion by activating the phosphorylation of eNOS at Ser(1179) and Ser(635) in a partly PKA-dependent manner.

• Authors: Xiang-Dong Li, Yu-Tong Cheng, Yue-Jin Yang, Xian-Min Meng, Jing-Lin Zhao, Hai-Tao Zhang, Yong-Jian Wu, Shi-Jie You, Yi-Ling Wu
• Journal: Microvascular research (Microvasc Res) Vol. 84 Issue 1 Pg. 44-54 (Jul 2012) ISSN: 1095-9319 [Electronic] United States
• PMID: 22542438 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical References

• Biomarkers
• Nitric Oxide Synthase Type III
• Cyclic AMP-Dependent Protein Kinases

Topics

• Animals
• Apoptosis
• Biomarkers (metabolism)
• Cyclic AMP-Dependent Protein Kinases (metabolism)
• Hemodynamics
• Ischemic Preconditioning
• Myocardial Reperfusion Injury (metabolism, pathology, physiopathology)
• Myocardial Stunning (metabolism, pathology, physiopathology)
• Myocardium (enzymology, pathology)
• Nitric Oxide Synthase Type III (metabolism)
• No-Reflow Phenomenon (metabolism, pathology, physiopathology)
• Phosphorylation
• Swine
• Swine, Miniature