Modification of contractile proteins by oxygen free radicals in rat heart

Abstract

This study was undertaken to investigate the effects of oxygen free radicals on myofibrillar creatine kinase activity. Isolated rat heart myofibrils were incubated with xanthine+xanthine oxidase (a superoxide anion radical-generating system) or hydrogen peroxide and assayed for creatine kinase activity. To clarify the involvement of changes in sulfhydryl groups in causing alterations in myofibrillar creatine kinase activity, 1) effects of N-ethylmaleimide (sulfhydryl groups reagent) on myofibrillar creatine kinase activity, 2) effects of oxygen free radicals on myofibrillar sulfhydryl groups content, and 3) protective effects of dithiothreitol (sulfhydryl groups-reducing agent) on the changes in myofibrillar creatine kinase activity due to oxygen free radicals were also studied. Xanthine+xanthine oxidase inhibited creatine kinase activity both in a time- and a concentration-dependent manner. Superoxide dismutase (SOD) showed a protective effect on the depression in creatine kinase activity caused by xanthine+xanthine oxidase. Hydrogen peroxide inhibited creatine kinase activity in a concentration-dependent manner; this inhibition was prevented by the addition of catalase. N-ethylmaleimide reduced creatine kinase activity in a dose-dependent manner. The content of myofibrillar sulfhydryl groups was decreased by xanthine+xanthine oxidase; this reduction was prevented by SOD. Furthermore, the depression in myofibrillar creatine kinase activity by xanthine+xanthine oxidase was protected by the addition of dithiothreitol. Oxygen free radicals may inhibit myofibrillar creatine kinase activity by modifying sulfhydryl groups in the enzyme protein. The reduction of myofibrillar creatine kinase activity may lead to a disturbance of energy utilization in the heart and may contribute to cardiac dysfunction due to oxygen free radicals.

Hydrogen Peroxide Activates Mitogen-Activated Protein Kinases and Na + -H + Exchange in Neonatal Rat Cardiac Myocytes

“…These results confirm previous studies by other groups, although both Goldhaber and Liu 6 and Kaneka et al 44 used at least 10-fold higher concentrations of OFRs. The relationship between MAP kinase-dependent increases in NHE activity and H 2 O 2 -induced contractile dysfunction remain to be established.…”

The cardioprotective potential of hydrogen sulfide in myocardial ischemia/reperfusion injury (Review)

“…Involvement of ROS in ischemia/reperfusion injury has been shown directly by spin trap α-phenyl-N-tert-butylnitrone (6, 62), luminal-enhanced tertbutyl-initiated chemiluminescence (38), and electron paramagnetic resonance spectroscopy (62); furthermore indirectly by the beneficial effects of various antioxidants in experimental ischemia-reperfusion models. Moreover exposure of the heart or subcellular organelles to oxyradical generating substances has been reported to produce similar effects to those observed in hearts subjected to ischemia/reperfusion (21). ROS can interact with important proteins, such as ion channels, sarco-endoplasmic reticulum calcium release channels and myofilament proteins which are associated with the excitation-contraction coupling.…”

Effects of reactive oxygen species on myofilament function in a rabbit coronary artery ligation model of heart failure

“…Previous investigations have shown that the contractile proteins are a potential target for the deleterious actions of O 2 -the superoxide anion and HOCl [12,15,16,17,25]. The present study demonstrates that altered crossbridge function in an animal model of chronic heart failure does not result in a modified response to exogenously applied oxidants.…”