Peroxynitrite inhibits myofibrillar protein function in an in vitro assay of motility

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• 作者：Jeremy H. Snook ; Jiahui Li ; Brian P. Helmke ; William H. Guilford
• 关键词：Myosin ; Actin ; Oxidative stress ; Cardiac muscle ; Free radicals
• 刊名：Free Radical Biology and Medicine
• 出版年：2008
• 出版时间：1 January 2008
• 年：2008
• 卷：44
• 期：1
• 页码：14-23
• 全文大小：548 K

文摘

We determined the effects of peroxynitrite (ONOOp>−p>) on cardiac myosin, actin, and thin filaments in order to more clearly understand the impact of this reactive compound in ischemia/reperfusion injury and heart failure. Actin filaments, native thin filaments, and α-cardiac myosin from rat hearts were exposed to ONOOp>−p> in the presence of 2 mM bicarbonate. Filament velocities over myosin, calcium sensitivity, and relative force generated by myosin were assessed in an in vitro motility assay in the absence of reducing agents. ONOOp>−p> concentrations ≥ 10 μM significantly reduced the velocities of thin filaments or bare actin filaments over α-cardiac myosin when any of these proteins were exposed individually. These functional deficits were linearly related to the degree of tyrosine nitration, with myosin being the most sensitive. However, at 10 μM ONOOp>−p> the calcium sensitivity of thin filaments remained unchanged. Cotreatment of myosin and thin filaments, analogous to the in vivo situation, resulted in a significantly greater functional deficit. The load supported by myosin after ONOOp>−p> exposure was estimated using mixtures experiments to be increased threefold. These data suggest that nitration of myofibrillar proteins can contribute to cardiac contractile dysfunction in pathologic states in which ONOOp>−p> is liberated.