High K+ cardioplegic solutions are used to arrest the heart during cardiac surgical procedure and to protect the heart tissue from the ischemic injury. However, the depolarization of the heart cell induced by high K+ could increase Ca2+ influx,
and
results in irreversible cardiac contracture due to intracellular Ca2+ loading(reperfusion injury). Since intracellular Ca2+ activities are coupled to Na+ activities via Na+ -Ca2+ exchange, an increased in intracellular Na+ activities during the
cardioplegia could cause an abrupt Ca2+ influx when referfused.
To study the effects of Na+ and Ca2+ exchange on myocardial protection after cardioplegia, some parameters of heart rate, time to recovery, time to first beat and contractility were measured in Langendorff perfusion system.
@ES The results are as follows:
@EN 1. The decreasing effect on heart beat was reduced by 98mM Na+ and 0.3mM Ca2+ solution with statistical significance.
2. the recovery time to the steady-state beating was faster after the cardioplegia with 98mM Na+ and 0.3mM Ca2+ solution.
3. The cardioplegia with various Na+ and Ca2+ concentrations had no significant effects on the maximum contractility of the recovery.
4. The cardioplegia with various Na+and CA2_ concentrations had no significant effects on the time to the first beat after cardioplegia.
From these results, it can be summarized that Na+ -Ca2+ exchange mechanism may play an importqnat role in recovery after cardioplegia, and the reduction of intracellular Na+ activities with cardioplegic solution of adjusted Na+ and Ca2+
concentration
based on Na+-Ca2+ exchange could prevent the reperfusion injury.
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