Hendriks F F, Jonas J, van der Laarse A, Huysmans H A, van Rijk-Zwikker G L, Schipperheyn J J
Ann Thorac Surg. 1985 Apr;39(4):312-7. doi: 10.1016/s0003-4975(10)62620-3.
Isolated pumping rat hearts, perfused with reconstituted blood, were studied to compare the effects of 30 minutes of ischemic arrest following calcium-free or normal, calcium-containing cold cardioplegia on recovery of mechanical function, lactate production, myocardial adenosine triphosphate concentration, and release of creatine kinase (CK). As in clinical situations, the volume of the infusate was only three to four times the intracavitary blood volume. Hearts arrested with calcium-free solution showed incomplete recovery of mechanical function, whereas hearts arrested with calcium-containing solution recovered completely. After calcium-free arrest, stroke volume recovered to 76 +/- 29% (standard deviation [SD]) of its prearrest value. Enzyme release (CK) was significantly higher after calcium-free cardioplegia (7.7 +/- 4.6 units [SD]) than after cardioplegia with normal calcium (2.1 +/- 1.6 units [SD]). Since the addition of only 0.025 mmol calcium ions to a liter of calcium-free solution completely prevented its negative effect, it was concluded that calcium-free cardioplegia may cause limited but pronounced damage to myocardial cells, presumably because it removes calcium from the cellular membranes--the so-called calcium paradox. Probably due to residual calcium in blood and extracellular fluid, the damage is not so extensive after calcium-free cardioplegia as to be noticeable in clinical surgical situations. Residual calcium in the heart does not exclude the possibility, however, that a calcium paradox occurs in small scattered areas of the heart.
对用再灌注血液灌注的离体大鼠心脏进行了研究，以比较无钙或正常含冷心脏停搏液停搏30分钟后，对机械功能恢复、乳酸生成、心肌三磷酸腺苷浓度以及肌酸激酶（CK）释放的影响。与临床情况一样，灌注液的体积仅为心腔内血容量的三到四倍。用无钙溶液停搏的心脏机械功能恢复不完全，而用含钙溶液停搏的心脏则完全恢复。无钙停搏后，每搏输出量恢复到停搏前值的76±29%（标准差[SD]）。无钙心脏停搏后酶释放（CK）（7.7±4.6单位[SD]）明显高于正常钙心脏停搏后（2.1±1.6单位[SD]）。由于在一升无钙溶液中仅添加0.025毫摩尔钙离子就完全防止了其负面影响，因此得出结论，无钙心脏停搏可能会对心肌细胞造成有限但明显的损伤，推测是因为它从细胞膜中去除了钙，即所谓的钙反常。可能由于血液和细胞外液中残留的钙，无钙心脏停搏后的损伤在临床手术情况下并不那么广泛以至于无法察觉。然而，心脏中的残留钙并不能排除心脏小而分散区域发生钙反常的可能性。
