EFFECT OF SHORT PERIODS OF ISCHEMIA ON PO STISCHEMIC REPERFUSION DISTURBANCES OF MYOCARDIAL-CONTRACTILITY IN ISOLATED RAT-HEART

Experiments were done on isolated perfused hearts (Langendorf) of male Wistar rats at 37 degrees C. Preloaded (2 g) hearts of control animal s were perfused for 50 min and then subjected to 30 min of total ische mia with subsequent reperfusion. Hearts of the second group of animals were subjected to 2 short periods (2 - 3 min each) followed by long p eriod (30 min) of total ischemia. Long period of total ischemia was fo llowed by reperfusion as in control group. Hearts of the second group were considered to be ''trained to ischemia''. During reperfusion of ' 'trained'' hearts duration of arrhythmia and magnitude of contraction were substantially tower while force of contraction and its increment in response to adrenaline and maximal preload were higher than those i n control hearts. This was associated with better preservation of cont raction force until period of prolonged ischemia and more rapid decrea se of heart rate during this period of ischemia.