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J. Exp. Med.,
Volume 189, Number 11, June 7, 1999 1699-1706
By

From the * Division of Cardiology, The First Department of Medicine, Osaka University Medical
School, Suita, Osaka 565-0871, Japan; and the Epidemiologic investigations have shown that exercise reduces morbidity and mortality from
coronary artery disease. In this study, using a rat model, we attempted to determine whether
exercise can reduce ischemic injury to the heart and elucidate a mechanism for the cardioprotective effect of exercise. Results showed that exercise significantly reduced the magnitude of a
myocardial infarction in biphasic manner. The time course for cardioprotection resembled that
of the change in manganese superoxide dismutase (Mn-SOD) activity. The administration of
the antisense oligodeoxyribonucleotide to Mn-SOD abolished the expected decrease in infarct
size. We showed that the level of tumor necrosis factor
Cardiovascular Division, Osaka Rosai Hospital,
Sakai, Osaka 591-8025, Japan
(TNF-
) and interleukin 1
(IL-1
)
increased after exercise. The simultaneous administration of the neutralizing antibodies to the
cytokines abolished the exercise-induced cardioprotection and the activation of Mn-SOD. Furthermore, TNF-
can mimic the biphasic pattern of cardioprotection and activation of
Mn-SOD. An antioxidant completely abolished cardioprotection and the activation of Mn-SOD by exercise or the injection of TNF-
as well as exercise-induced increase in TNF-
and
IL-1
. The production of reactive oxygen species and endogenous TNF-
and IL-1
induced
by exercise leads to the activation of Mn-SOD, which plays major roles in the acquisition of
biphasic cardioprotection against ischemia/reperfusion injury in rats.
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