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

许多研究者报道了多剂量输注晶体心脏截止剂对未成熟心肌的损害。我们研究了多剂量冷血停搏（CBC）对未成熟心肌的影响，并与圣托马斯停搏（ST）进行了比较。采用Langendorff法对新生兔（6 ~ 9 d）心脏缺血前后37℃灌注。采用核磁共振波谱法评估心肌活力，以缺血前值的%表示（mean * SE）。采用干湿法测定心肌含水量。未成熟的心脏（每组5个）在缺血3小时内，在15℃时接受每次10ml的心脏麻痹溶液单次输注或多次输注（间隔15、30或60分钟）。再灌注30min后。单次给药能较好地恢复ATP(91.7 * 2.6%)，但频繁给药会使ATP恢复恶化（63.1 * 5.0%）。间隔组（p<0.01）。相比之下，间隔15 min CBC的ATP恢复效果最好（95.1 * 3.6%），多剂量CBC可改善缺血后ATP恢复（单剂量组75.1 * 3.7%，与多剂量组相比p<0.05）。ST组心肌含水量显著高于CBC组，但与ATP恢复无关。这些观察结果表明，多剂量心脏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注方法的组合更敏感。综上所述，我们必须为所采用的心脏麻痹液寻找一种合适的输注方法。

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.