Lodge N J, Bassett A L, Gelband H
Pflugers Arch. 1985 Sep;405(1):37-45. doi: 10.1007/BF00591095.
45Ca2+ exchange was studied in small pieces of canine left ventricular free wall. The loss of 45Ca2+ from 45Ca2+ equilibrated tissue into ice-cold (4 degrees C) "wash" medium could be best fitted with a model containing a minimum of 3 compartments. 45Ca2+ uptake into and 45Ca2+ efflux from the most slowly exchanging compartment (compartment 3) at 37 degrees C allowed it to be subdivided into two fractions; a rapidly exchanging fraction (t1/2 approximately 1.25 min) and a slowly exchanging fraction (t1/2 approximately 50 min). The total Ca2+ content of compartment 3 was enhanced by isoproterenol but little affected by caffeine. The slow t1/2 for exchange of the Ca2+ in compartment 3 at 4 degrees C and its increased Ca2+ content following isoproterenol treatment suggest that this compartment contains some Ca2+ of intracellular origin. In addition, the finding that the rapidly exchanging part of compartment 3 could be preserved by cooling the tissue to 4 degrees C shows that rapidly exchanging Ca2+ compartments can be studied in superfused cardiac preparations using this technique. Action potentials, elicited by electrical stimulation of the tissue, caused large changes in the Ca2+ content of compartment 3 (up to 170 muM/kg) indicating that this postulated intracellular compartment may play a significant role in the normal contraction-relaxation cycle.
对犬左心室游离壁小块组织中的(^{45}Ca^{2 +})交换进行了研究。将(^{45}Ca^{2 +})平衡的组织置于冰冷（4℃）的“冲洗”培养基中时，(^{45}Ca^{2 +})的流失情况最适合用一个至少包含3个区室的模型来拟合。在37℃下，(^{45}Ca^{2 +})进入和流出交换最慢的区室（区室3）的情况使其可细分为两个部分；一个快速交换部分（半衰期约1.25分钟）和一个缓慢交换部分（半衰期约50分钟）。异丙肾上腺素可增加区室3的总钙含量，但咖啡因对其影响较小。区室3中钙离子在4℃时交换的半衰期较长，且经异丙肾上腺素处理后其钙含量增加，这表明该区室含有一些细胞内源性的钙。此外，将组织冷却至4℃可保留区室3中快速交换部分这一发现表明，使用该技术可以在灌注心脏标本中研究快速交换的钙离子区室。通过电刺激组织引发的动作电位会使区室3的钙含量发生大幅变化（高达170μM/kg），这表明这个假定的细胞内区室可能在正常的收缩 - 舒张周期中发挥重要作用。
