Pre-conditioning with adenosine leads to concentration-dependent infarct size reduction in the isolated rabbit heart

Adenosine (ADO) has a cardioprotective effect in ischemia-reperfusion injury when administered both prior to ischemia and during reperfusion. ADO has also been implicated in the mechanism of ischemic pre-conditioning. The aim of this study was to investigate whether there was a concentration-response between the administration of ADO prior to ischemia-reperfusion and reduction in subsequent infarct size. Rabbit isolated perfused hearts were subjected to 45 min ischemia and 180 min reperfusion following pre-treatment with either Krebs Henseleit buffer alone or buffer containing ADO at a range of concentrations (3 micro M-100 micro M) for 5 min followed by 5 min perfusion with buffer. Infarct/risk ratios were significantly reduced in hearts pre-perfused with higher (> 3 micro M) concentrations of ADO (Control, 58.5 +/- 1.5%; 3 micro M ADO, 51.6 +/- 3.0% ; 6 micro M ADO, 44.1% +/- 2.0%; 10 micro M ADO, 33.3 +/- 1.9%; 20 micro M ADO, 26.6 +/- 0.9%; 50 micro M ADO, 21.6 +/- 3.5%; 100 micro M ADO, 23.0 +/- 0.6%). We conclude that pre-treatment with ADO leads to a concentration-dependent reduction in infarct size.