OXIDATIVE STRESS AND HEART-FAILURE

Various abnormalities have been implicated in the transition of hypert rophy to heart failure but the exact mechanism is still unknown. Thus heart failure subsequent to hypertrophy remains a major clinical probl em. Recently, oxidative stress has been suggested to play a critical r ole in the pathogenesis of heart failure. Here we describe antioxidant changes as well as their significance during hypertrophy and heart fa ilure stages. Heart hypertrophy in rats and guinea pigs, in response t o pressure overload, is associated with an increase in 'antioxidant re serve' and a decrease in oxidative stress. Hypertrophied rat hearts sh ow increased tolerance for different oxidative stress conditions such as those imposed by free radicals, hypoxia-reoxygenation and ischemia- reperfusion. On the other hand, heart failure under acute as well as c hronic conditions is associated with reduced antioxidant reserve and i ncreased oxidative stress. The latter may have a causal role as sugges ted by the protection seen with antioxidant treatment in acute as well as in chronic heart failure. It is becoming increasingly apparent tha t, anytime the available antioxidant reserve in the cell becomes inade quate, myocardial dysfunction is imminent.