Calcium but not Amiloride Improves the Mechanical Function of Reperfused One-Week-Old Rabbit Hearts
It is hypothesized that intracellular Ca2+ overload is a cause of prolonged post-ischemic ventricular dysfunction. We studied the effects of amiloride and of increasing extracellular Ca2+ concentration on the functional recovery of isolated reperfused imature rabbits.
Isolated working hearts from one-week-old rabbits were subjected to a 40-minute period of global ischemia followed by 30 minutes of aerobic reperfusion. Contractile function was 45% of the preischemic level in hearts reperfused with buffer containing 1.75 mM Ca2+ (group 1). No significant difference in recovery of mechanical function was seen between hearts in which 300 μM amiloride was added five minutes before the onset of ischemia (group 2) and in hearts of group 1. When Ca2+ was increased to 2.5 mM during reperfusion (group 3), mechanical function was significantly recovered to 128% of the preischemic level, There were no significant differences in efflux of both lactate and creatine phosphokinase among the three groups.
Therefore, we conclude that, unlike the adult heart, increasing Ca2+ during reperfusion may be beneficial for reperfused one-week-old rabbit hearts rather than adding amiloride five minutes before ischemia.
KeywordsHeart Circ Rabbit Heart Adult Heart Immature Heart Mature Heart
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