TY - JOUR
T1 - Late preconditioning against stunning is not mediated by increased antioxidant defenses in conscious pigs
AU - Tang, Xian Liang
AU - Qiu, Yumin
AU - Turrens, Julio F.
AU - Sun, Jian Zhong
AU - Bolli, Roberto
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1997
Y1 - 1997
N2 - Previous studies in conscious pigs have demonstrated that a sequence of ten 2-min coronary occlusion/2-min reperfusion cycles renders the heart relatively resistant to myocardial stunning 24 h later [late preconditioning (PC) against stunning] by an unknown mechanism. Since oxygen radicals contribute importantly to myocardial stunning and since antioxidant enzymes have been reported to be upregulated 24 h after PC in dogs and rabbits, we tested the hypothesis that late PC against stunning is related to an increase in endogenous antioxidant defenses. Chronically instrumented conscious pigs underwent a sequence of ten 2-min coronary occlusion/2-min reperfusion cycles (preconditioned group, n = 11) or received no intervention (control group, n = 5). Twenty-four hours later, pigs were killed and the myocardial levels of Mn superoxide dismutase (SOD), Cu-Zn SOD, catalase, glutathione (GSH) peroxidase. GSH reductase, GSH, GSH disulfide, α-tocopherol, and ascorbate were measured. There were no differences in any of the enzymatic or nonenzymatic antioxidants between the ischemic and nonischemic regions in the preconditioned group or between the control and the preconditioned group. Thus, when a marked protection against stunning was present (24 h after PC), no alteration in antioxidant defenses was observed. These results indicate that, in conscious pigs, late PC against myocardial stunning is not mediated by increased endogenous antioxidant defenses, thereby refuting one of the major current hypotheses regarding this phenomenon.
AB - Previous studies in conscious pigs have demonstrated that a sequence of ten 2-min coronary occlusion/2-min reperfusion cycles renders the heart relatively resistant to myocardial stunning 24 h later [late preconditioning (PC) against stunning] by an unknown mechanism. Since oxygen radicals contribute importantly to myocardial stunning and since antioxidant enzymes have been reported to be upregulated 24 h after PC in dogs and rabbits, we tested the hypothesis that late PC against stunning is related to an increase in endogenous antioxidant defenses. Chronically instrumented conscious pigs underwent a sequence of ten 2-min coronary occlusion/2-min reperfusion cycles (preconditioned group, n = 11) or received no intervention (control group, n = 5). Twenty-four hours later, pigs were killed and the myocardial levels of Mn superoxide dismutase (SOD), Cu-Zn SOD, catalase, glutathione (GSH) peroxidase. GSH reductase, GSH, GSH disulfide, α-tocopherol, and ascorbate were measured. There were no differences in any of the enzymatic or nonenzymatic antioxidants between the ischemic and nonischemic regions in the preconditioned group or between the control and the preconditioned group. Thus, when a marked protection against stunning was present (24 h after PC), no alteration in antioxidant defenses was observed. These results indicate that, in conscious pigs, late PC against myocardial stunning is not mediated by increased endogenous antioxidant defenses, thereby refuting one of the major current hypotheses regarding this phenomenon.
KW - Ascorbate
KW - Catelase
KW - Glutathione peroxidase
KW - Glutathione reductase
KW - Superoxide dismutase
KW - Tocopherol
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U2 - 10.1152/ajpheart.1997.273.4.h1651
DO - 10.1152/ajpheart.1997.273.4.h1651
M3 - Article
C2 - 9362227
AN - SCOPUS:0030662133
SN - 0363-6135
VL - 273
SP - H1651-H1657
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 4 42-4
ER -