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Titolo:
OXIDATIVE STRESS MODIFIES THE ACTIVITY OF CARDIAC SARCOLEMMAL PHOSPHOLIPASE-C
Autore:
MEIJ JTA; SUZUKI S; PANAGIA V; DHALLA NS;
Indirizzi:
ST BONIFACE GEN HOSP,RES CTR,DIV CARDIOVASC SCI,351 TACHE AVE WINNIPEG R2H 2A6 MB CANADA ST BONIFACE GEN HOSP,RES CTR,DIV CARDIOVASC SCI WINNIPEG R2H 2A6 MB CANADA UNIV MANITOBA,FAC MED,DEPT ANAT WINNIPEG MB CANADA UNIV MANITOBA,FAC MED,DEPT PHYSIOL WINNIPEG MB CANADA
Titolo Testata:
Biochimica et biophysica acta (G). General subjects
fascicolo: 1, volume: 1199, anno: 1994,
pagine: 6 - 12
SICI:
0304-4165(1994)1199:1<6:OSMTAO>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
OXYGEN FREE-RADICALS; SARCOPLASMIC-RETICULUM; REPERFUSION INJURY; HYDROGEN-PEROXIDE; HYPOCHLOROUS ACID; SULFHYDRYL-GROUPS; MULTIPLE FORMS; RAT HEARTS; DITHIOTHREITOL; METHYLATION;
Keywords:
PHOSPHOLIPASE C; PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE; HYDROGEN PEROXIDE; HYPOCHLOROUS ACID; SULFHYDRYL GROUPS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
38
Recensione:
Indirizzi per estratti:
Citazione:
J.T.A. Meij et al., "OXIDATIVE STRESS MODIFIES THE ACTIVITY OF CARDIAC SARCOLEMMAL PHOSPHOLIPASE-C", Biochimica et biophysica acta (G). General subjects, 1199(1), 1994, pp. 6-12

Abstract

We have examined the direct effects of oxidant metabolites on cardiacsarcolemmal phosphoinositide phospholipase C which transduces signalsfrom various receptors for the modulation of intracellular Ca2+ levels. The enzyme activity in rat cardiac sarcolemmal membranes that had been preincubated (10 min; 37 degrees C) with xanthine-xanthine oxidase, a superoxide anion generating system, was not significantly affected. The addition to this system of superoxide dismutase, which converts superoxide anion to hydrogen peroxide (H2O2), resulted in a significant decrease of the enzyme activity in comparison with control values. Such decrease was fully prevented by catalase. Preincubation of sarcolemma with hypochlorous acid also gave a significant inhibition of phospholipase C, which was counteracted by the synthetic thiol reducer dithiothreitol. H2O2-pretreatment induced a concentration-dependent inhibition of the enzyme which was prevented by catalase but not by the ironchelator deferoxamine. Dithiothreitol was able to protect against, aswell as to recover the enzyme activity from the H,Oz effects. These data suggest that superoxide anions and hydroxyl radicals did not interfere with phospholipase C activity, and that the nonradical oxidants, H2O2 and hypochlorous acid, may have acted through oxidation of thiol (SH) groups. The existence of reactive SH groups associated with the enzyme was confirmed by the inhibitory effects of SH modifiers (p-chloromercuriphenylsulfonic acid, 5'5'-dithio-bis(2-nitrobenzoic acid), N-ethylmaleimide and methyl methanethiosulfonate), which were prevented and in some cases also reversed by dithiothreithol. The biological reducer glutathione (CSH) was not able to recover the H2O2-induced inhibition of phospholipase C, whereas its oxidized form (GSSG) decreased theenzyme activity both in control and H2O2-pretreated membranes. The enzyme was active in a wide range of GSH/GSSG redox states, but H2O2 pretreatment narrowed this range. The results showed that oxidative stress changed the redox state of sarcolemmal phospholipase C, and this deactivated the enzyme. The oxidants' concentrations that significantly impaired phospholipase C in this study were compatible with those occurring in vivo during ischemia-reperfusion [Am. J. Med. 91(Suppl. 3C):235, 1991]. This supports the possibility that alteration of the receptor-associated phospholipase C may be a factor in the oxidant-related dysfunction of the ischemic-reperfused heart.

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Documento generato il 04/12/20 alle ore 03:43:24