Myocardial protective effects of adenosine. Infarct size reduction with pretreatment and continued receptor stimulation during ischemia.

BACKGROUNDWe hypothesized that 1) endogenous adenosine released during ischemia conferred an inherent cardioprotection, and 2) a pretreatment dose of adenosine before ischemia would provide additional protection independent of hemodynamic effects.METHODS AND RESULTSThirty-six anesthetized New Zealand White rabbits underwent 30 minutes of regional ischemia produced by coronary occlusion followed by 2 hours of reperfusion. The adenosine group (ADO, n = 9) received a 5-minute pretreatment infusion of 140 micrograms/kg/min of adenosine before ischemia. A control group (SAL, n = 9) received saline before ischemia. To separate the effects of adenosine used as a pretreatment versus the effects during ischemia, a third group (ADO+SPT, n = 9) received adenosine as pretreatment followed by 10 mg/kg 8-p-sulfophenyl theophylline (8-SPT), an A1/A2-receptor antagonist given before ischemia, thus allowing pretreatment with adenosine but antagonizing its effects during ischemia. To preclude any protection from endogenous...