ABSTRACT
It has been shown that reactive oxygen species produced during the early phase of myocardial post-ischemic reperfusion are one of the main causes of reperfusion injury. This observation has led to various antioxidant strategies using many reactive oxygen species scavengers, including manganese complexes. The aim of the present work was to provide a reference study of the effects of manganese itself (MnCl2) on isolated rat hearts submitted to global total normothermic ischemia (30 min) and reperfusion (60 min). McCl2 was administered either during the first 10 min reperfusion (10(-5)M and 10(-4)M) or throughout reperfusion (10(-4)M). After 10 min reperfusion, no functional difference was evidenced between control and manganese-treated groups, whereas high energy phosphate contents were significantly higher in treated groups. MnCl2 10(-4)M enhanced the recovery of developed pressure between 40 and 55 min reperfusion. At the end of reperfusion, hearts treated during the first 10 min reperfusion showed a better metabolic recovery. The group treated throughout reperfusion showed a better metabolic recovery, but a reduced coronary flow and a weak recovery of developed pressure. These results suggest that MnCl2, administered during the early phase of reperfusion, protects against myocardial reperfusion injury. This effect might be mediated by manganese antioxidant properties.