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Adenosine-enhanced ischemic preconditioning decreases infarct in the regional ischemic sheep heart
M Uematsu1, G R Gaudette, J O Laurikka
1Division of Cardiothoracic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA.
Background:
Recently we have reported a myoprotective protocol, adenosine-enhanced ischemic preconditioning, that extends the protection afforded by ischemic preconditioning in the isolated crystalloid-perfused heart. In this report the efficacy of adenosine-enhanced ischemic preconditioning in the in situ blood-perfused heart was investigated.
Methods:
Sheep were subjected to 60 minutes of regional ischemia and 120 minutes of reperfusion. Ischemic preconditioned hearts received 5 minutes of zero flow regional ischemia and 5 minutes of reperfusion before regional ischemia. Adenosine-enhanced ischemic preconditioned hearts received a bolus injection of 10 mmol adenosine at the immediate start of ischemic preconditioning. Adenosine-treated hearts received an adenosine bolus, 10 minutes before regional ischemia. The ratio of infarct size to area at risk and mechanical function were determined.
Results:
The infarct size to area at risk ratio in regional ischemia was 55.4%+/-2.1%. This ratio was significantly decreased with ischemic preconditioning and adenosine (22.2%+/-2.2% and 19.3%+/-1.4%, respectively; p < 0.001 versus regional ischemia) and adenosine-enhanced ischemic preconditioning (8.0%+/-2.0%, p < 0.001 versus regional ischemia and ischemic preconditioning, and p < 0.01 versus adenosine).
Conclusions:
Adenosine-enhanced ischemic preconditioning significantly decreases infarct size in the in situ blood-perfused heart and provides superior protection compared with ischemic preconditioning.