Activation of proteolytic enzymes and depression of the sarcolemmal Na+/K+-ATPase in ischemia-reperfused heart may be mediated through oxidative stress.
We tested whether the activation of proteolytic enzymes, calpain, and matrix metalloproteinases (MMPs) during ischemia-reperfusion (I/R) is mediated through oxidative stress. For this purpose, isolated rat hearts were subjected to a 30 min global ischemia followed by a 30 min reperfusion. Cardiac function was monitored and the activities of Na(+)/K(+)-ATPase, Mg(2+)-ATPase, calpain, and MMP were measured. Depression of cardiac function and Na(+)/K(+)-ATPase activity in I/R hearts was associated with increased calpain and MMP activities. These alterations owing to I/R were similar to those observed in hearts perfused with hypoxic medium, H(2)O(2) and xanthine plus xanthine oxidase. The I/R-induced changes were attenuated by ischemic preconditioning as well as by perfusing the hearts with N-acetylcysteine or mercaptopropionylglycine. Inhibition of MMP activity in hearts treated with doxycycline depressed the I/R-induced changes in cardiac function and Na(+)/K(+)-ATPase activity without affecting the calpain activation. On the other hand, inhibition of calpain activity upon treatment with leupeptin or MDL 28170 significantly reduced the MMP activity in addition to attenuating the I/R-induced alterations in cardiac function and Na(+)/K(+)-ATPase activity. These results suggest that the I/R-induced depression in Na(+)/K(+)-ATPase and cardiac function may be a consequence of the increased activities of both calpain and MMP because of oxidative stress in the heart.
Institute of Cardiovascular Sciences, St. Boniface Hospital Research, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada.
Raja B
RB
Singh
Larry
L
Hryshko
Darren
D
Freed
Naranjan S
NS
Dhalla
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015536:Down-Regulation; D004789:Enzyme Activation; D000860:Hypoxia / Q000201:enzymology; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000503:physiopathology / Q000517:prevention & control; D009206:Myocardium / Q000201:enzymology*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010477:Perfusion; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012508:Sarcolemma / Q000187:drug effects / Q000201:enzymology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013997:Time Factors; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
D000975:Antioxidants; D061965:Matrix Metalloproteinase Inhibitors; D016877:Oxidants; D011480:Protease Inhibitors; D002154:Calpain; D020782:Matrix Metalloproteinases; D000254:Sodium-Potassium-Exchanging ATPase