Evaluation of immature myocardial energy metabolism during ischemia and after reperfusion by NMR spectroscopy

许多研究人员报道，多剂量输注晶体停搏液对未成熟心肌有害。我们观察了多剂量冷血停搏液(CBC)对未成熟心肌的影响，并与圣托马斯停搏液(ST)进行了比较。新生兔(6~9日龄)的心脏在缺血前和缺血后37℃用朗宁多夫方法进行灌流。用核磁共振波谱评价心肌存活率，并以缺血前心肌活力的百分比(Mean*SE)表示。用湿法和干法测定心肌含水量。未成熟心脏(每组5个)在缺血3小时内以15oC的温度接受每种停搏液10毫升的单次输注或多次输注(间隔15、30或60分钟)。再灌流30min后，单次给药对ATP的恢复良好(91.7±2.6%)，但频繁给药使ATP恢复更差(15min时为63.1±5.0%)。间歇给药组与单剂量组比较P&lt；0.01)。相比之下，间隔15分钟的CBC对ATP的恢复效果最好(95.1±3.6%)，多剂量CBC输注改善了缺血后的ATP恢复(单剂量组为75.1×3.7%，与多剂量组相比P&lt；0.05)。ST组心肌含水量明显高于CBC组，但与ATP恢复无关。这些观察表明，多剂量停搏液输注并不总是对未成熟心脏有害，未成熟心脏可能比成人心脏对停搏液和输液方法的组合更敏感。总之，我们必须为所采用的心脏停搏液寻找一种合适的输液方法。

Multidose infusion of crystalloid cardioplegia has been reported to be detrimental to immature myocardium by many investigators. We investigated the effect of multidose cold blood cardioplegia (CBC) on immature myocardium in comparison with St. Thomas' cardioplegia (ST). Hearts from neonatal rabbits (6-9 days) were perfused at 37 OC in the Langendorff method before and after ischemia. Myocardial viability was evaluated by NMR spectroscopy and was expressed in % of preischemic value (mean * SE). Myocardial water content was measured by the wet and dry method. Immature hearts (five in each group) received a single 10 ml infusion of each cardioplegic solution or multiple infusions ( at 15-, 30-, or 60-min.intervals ) at 15 OC during 3 hrs of ischemia. After reperfusion for 30 mins., a single dose of ST showed good recovery of ATP (91.7 * 2.6%), but more frequent infusions of ST worsened ATP recovery (63.1 * 5.0% in the 15-min. interval group,p<0.01 vs single-dose group). In contrast CBC at 15-min.intervals produced best recovery of ATP (95.1 * 3.6%), and multidose CBC infusion improved postischemic ATP recovery (75.1 * 3.7% in single-dose group, p<0.05 vs multidose groups). Myocardial water contents in ST groups were significantly higher than in CBC groups, however, they had no relationship with ATP recovery. These observations suggest that multidose cardioplegic infusion is not always detrimental to the immature heart and that the Immature heart may be more sensitive than the adult heart to the combination of cardioplegic solution and infusion method. In conclusion we have to find a suitable infusion method for the cardioplegic solution adopted.