HYPOTHERMIA INCREASES THE THRESHOLD FOR ISCHEMIC PRECONDITIONING
Kentaro Dote, Roger A. Wolff, Donna M. Van Winkle
The Journal of Thoracic and Cardiovascular Surgery, 1998Rabbit hearts underwent 45 minutes of regional ischemia, followed by 2 hours of reperfusion. Either normothermic or hypothermic ischemic preconditioning was elicited by either one or four periods of 5 minutes of regional ischemia. Normothermic ischemic preconditioning with one cycle had a 58% reduction and four cycles had a 95% reduction. Hypothermic ischemic preconditioning with four cycles of 5-minute coronary occlusions resulted in a 94% reduction of infarct size but hypothermic ischemic preconditioning with one cycle resulted in no reduction of infarct size. Myocardial glycogen and lactate levels were maintained near control levels during hypothermic ischemia. Hypothermia during the preconditioning period increases the threshold for eliciting the infarct limitation of ischemic preconditioning.