We investigated isolated guinea pig hearts (n = 121) in an ischemia/ reperfusion model with the aim to compare the efficiency of the cardioplegic solution HTK with its novel replacement HTKN.

Following consolidation with Tyrode's solution, ischemia started either immediately or after preceding cardioplegia with HTK, HTKN, or modified HTK enriched with Ca. Ischemia lasted either 80 min at 30 °C, or 360 min at 5 °C, or 81 min at 30 °C with intermittent cardioplegic perfusion. During ischemia we measured intracellular calcium (iCa⁺⁺) and the time of gap junction uncoupling (t-in). During reperfusion we measured the reestablishment of cell coupling (t-ret), left ventricular developed pressure (LVDP), and heart rhythm (VC-RR).

In 5 °C groups, iCa⁺⁺ at t-in was significantly higher than before ischemia, and longest t-in, shortest t-ret, and best VC-RR were observed after HTK-protection. Of all 30 °C groups, the intermittent group with modified HTK showed shortest t-ret, best VC-RR, and the highest LVDP. At 5 °C, HTK groups had higher LVDP than HTK-N groups, but not at 30 °C.

The data suggest that the higher calcium level in the HTK-N solution improves reperfusion after short ischemia at 30 °C but for long lasting ischemia at 5 °C it is beneficial to use the HTK solution.

我们在局部缺血/再灌注模型中研究了孤立的豚鼠心脏（n = 121），目的是比较心脏停搏液HTK和其新型替代HTK N的效率。

在与Tyrode's解决方案合并后，缺血立即开始，也可能在之前的HTK，HTK N或富含Ca的改良型HTK心脏停搏后开始。缺血在30°C下持续80分钟，在5°C下持续360分钟，在30°C下持续81分钟，并伴有间歇性心脏停搏。在缺血期间，我们测量了细胞内钙（iCa ⁺⁺）和间隙连接解偶联的时间（t-in）。在再灌注过程中，我们测量了细胞偶联（t-ret），左心室发育压力（LVDP）和心律（VC-RR）的重建。

在5°C组中，t-in的iCa ⁺⁺明显高于缺血前，HTK保护后观察到最长的t-in，最短的t-ret和最佳的VC-RR。在所有30°C组中，具有改良的HTK的间歇组显示出最短的t-ret，最佳的VC-RR和最高的LVDP。在5°C时，HTK组的LVDP高于HTK-N组，但在30°C时则没有。

数据表明，HTK-N溶液中较高的钙水平可改善30°C的短暂缺血后的再灌注，但对于5°C的长期缺血，使用HTK溶液是有益的。