Ischaemic and hypoxic preconditioning enhance postischaemic recovery of function in the rat heart

Objective: The aims were (1) to determine whether ischaemic and hypoxic preconditioning enhance recovery of left ventricular function after global ischaemia in the rat, and (2) to evaluate the effects of selective adenosine A1 receptor antagonists on ischaemic and hypoxic preconditioning. Methods: Isolated rat hearts, perfused at constant pressure, were subjected to 30 min ischaemia and 30 min reperfusion. Control hearts were compared to hearts preconditioned with 5 min ischaemia in the presence or absence of the adenosine A1 antagonist AI433U (10 μM), and hearts preconditioned with 5 min hypoxia in the presence or absence of the adenosine A1 antagonist 8-cyclopentyl-l,3-dipropylxanthine (DPCPX, 5 μM). Recovery of left ventricular function was assessed by percent recovery of preischaemic rate-pressure product. Results: Control hearts recovered 64(SEM 4)% of preischaemic rate-pressure product after 30 min reperfusion, whereas ischaemic and hypoxic preconditioned hearts recovered 86(3)% and 94(5)%, respectively (p