Ouabain triggers preconditioning through activation of the Na+,K+-ATPase signaling cascade in rat hearts.
OBJECTIVE
Because ouabain activates several pathways that are critical to cardioprotective mechanisms such as ischemic preconditioning, we tested if this digitalis compound could protect the heart against ischemia-reperfusion injury through activation of the Na+,K+-ATPase/c-Src receptor complex.


RESULTS
In Langendorff-perfused rat hearts, a short (4 min) administration of ouabain 10 muM followed by an 8-minute washout before 30 min of global ischemia and reperfusion improved cardiac function, decreased lactate dehydrogenase release and reduced infarct size by 40%. Western blot analysis revealed that ouabain activated the cardioprotective phospholipase Cgamma1/protein kinase Cepsilon (PLC-gamma1/PKCepsilon) pathway. Pre-treatment of the hearts with the Src kinase family inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolol[3,4-d]pyrimidine (PP2) blocked not only ouabain-induced activation of PLC-gamma1/PKCepsilon pathway, but also cardiac protection. This protection was also blocked by a PKCepsilon translocation inhibitor peptide (PKCepsilon TIP).


CONCLUSIONS
Short exposure to a low concentration of ouabain protects the heart against ischemia/reperfusion injury. This effect of ouabain on the heart is most likely due to the activation of the Na+,K+-ATPase/c-Src receptor complex and subsequent stimulation of key mediators of preconditioning, namely PLC-gamma1 and PKCepsilon.
Pierre
Sandrine V
SV
Department of Physiology, Pharmacology, Metabolism and Cardiovascular Sciences, Medical University of Ohio, 3035 Arlington Avenue, Toledo, OH 43614-5804, USA.
Yang
Changjun
C
Yuan
Zhaokan
Z
Seminerio
Jennifer
J
Mouas
Christian
C
Garlid
Keith D
KD
Dos-Santos
Pierre
P
Xie
Zijian
Z
D000818:Animals; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019157:Ischemic Preconditioning, Myocardial; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008297:Male; D023421:Models, Animal; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D010042:Ouabain / Q000627:therapeutic use*; D010477:Perfusion; D051744:Protein Kinase C-epsilon / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
C412373:AG 1879; D004791:Enzyme Inhibitors; D011743:Pyrimidines; D010042:Ouabain; D007770:L-Lactate Dehydrogenase; D019061:src-Family Kinases; D051744:Protein Kinase C-epsilon; D000254:Sodium-Potassium-Exchanging ATPase