PROTECTION INDUCED BY A BRIEF ISCHEMIC EPISODE IN THE LANGENDORFF PERFUSED RAT-HEART

Rationale and Objectives. Ischemic episodes lasting approximately 1 mi n may be associated with coronary angioplasty. We explored whether suc h episodes could induce myocardial protection against prolonged ischem ic episodes in an ex vivo model. Methods. Protection afforded by pretr eatment with a 1-min ischemic episode (ischemic preconditioning) again st prolonged ischemia was investigated in the isolated rat heart. Left ventricular developed pressure (LVDP; LV systolic pressure - LV end-d iastolic pressure), heart rate (HR), and enzyme leakage (lactate dehyd rogenase) were indexes of protection. Results. An increased recovery o f LVDP x HR after 16 and 19 min of ischemia of 37% and 28%, respective ly, paralleled by reduced enzyme leakage, was observed in precondition ed hearts after 10 min of reperfusion. However, the difference between preconditioned and control hearts was lost after 30 min of reperfusio n. Conclusion. Ischemic episodes lasting approximately 1 min are not s ufficient to initiate stable protection even if initial functional and metabolic indexes suggest a protective effect.