Importance of endogenous adenosine during ischemia and reperfusion in neonatal porcine hearts

Adenosine has several potentially cardioprotective effects. We hypothesized that the effects of endogenous adenosine vary with degree of ischemia and that elevating endogenous levels is protective. Isolated blood-perfused piglet hearts underwent 120 minutes of low-flow ischemia (10% flow) or 90 minutes of zero-flow ischemia, all with 60 minutes of reperfusion. Hearts were treated with either saline, the adenosine receptor blocker 8-sulfophenyltheophylline (8SPT, 300 micromol x L(-1)), or the nucleoside transport inhibitor draflazine (1 micromol x L(-1)). In separate groups, biopsies were obtained before and at the end of ischemia. Compared with saline, 8SPT did not significantly alter functional recovery in either protocol. Draflazine significantly improved percent recovery of left ventricular systolic pressure both in the low-flow protocol (92+/-3% versus 75+/-2% [saline] and 73+/-3% [8SPT], P