Melatonin, a pineal gland-derived hormone, is important for the control of our daily sleep-wake cycles, and exhibits a circadian secretary pattern. Recent evidence has demonstrated that melatonin is a potent antioxidant. Studies of many tissue types show the damage associated with production of oxygen varients (reactive oxygen species - ROS). Ischemia-reperfusion injury, a condition caused by the reduction and subsequent restoration of blood flow, leads to severe tissue damage. Melatonin appears to prevent ischemic brain injury, a syndrome which has been attributed to the damaging effects of ROS. ROS have also been implicated in some forms of programmed cell death (apoptosis).

Cardiac ischemic-reperfusion injury (IR) is a serious clinical condition which causes an impairment of cardiac muscle function resulting in death of muscle cells and may be fatal. It has been speculated that ROS also play a role in the cardiac damage associated with coronary artery disease as well as other systemic conditions such as septic shock. Whether melatonin protects the heart against ROS damage has not been explored.

Utilizing the isolated heart cell model, investigators at RSRF are examining the effects of naturally occurring ROS generating compounds such as endotoxin and determine whether pretreatment with physiologically relevant doses of melatonin will block the effects. If effective, melatonin could be of therapeutic value to prevent cardiac damage from IR injury and septic shock as well as during clinical procedures such as cardiac catheterization.