Balla T, Szebeny M, Kanyar B, Spät A
Cell Calcium. 1985 Aug;6(4):327-42. doi: 10.1016/0143-4160(85)90003-x.
The aim of the present study was to examine the effect of angiotensin II on the different pools of exchangeable Ca2+ in isolated rat adrenal glomerulosa cells. On the basis of steady state analysis of 45Ca exchange curves at least three kinetically distinct Ca2+ compartments are present in these cells. The most rapidly exchangeable compartment was regarded as Ca2+ loosely bound to the glycocalyx and the other compartments were considered to be intracellular Ca2+ pools. The effect of angiotensin II on different intracellular compartments was examined by adding the hormone at different phases of Ca2+ washout. Angiotensin increased the rate of 45Ca efflux within 1.5 min when added at the beginning of the washout. This effect, however, could not be detected when the hormone was added at the 30th min of washout, indicating that at least one hormone sensitive pool had lost most of its radioactivity by this time. In contrast to angiotensin II, the mitochondrial uncoupler FCCP mobilized almost the same quantity of 45Ca irrespective of the time of its addition during the washout. This latter finding suggests that this presumably mitochondrial Ca2+ pool has a slow rate of exchange and thus differs from the pool initially mobilized by angiotensin II. The initial Ca2+ mobilizing effect of angiotensin II was also observed in a Ca2+-free media which contained EGTA, indicating that this effect is not triggered by increased Ca2+ influx. In the present study we demonstrate in the intact glomerulosa cell that angiotensin II mobilizes Ca2+ from an intracellular Ca2+ store which appears to be distinct from the FCCP-sensitive store.
本研究的目的是检测血管紧张素II对分离的大鼠肾上腺球状带细胞中不同可交换钙池的影响。基于对45Ca交换曲线的稳态分析，这些细胞中至少存在三个动力学上不同的钙区室。最快速可交换的区室被认为是与糖萼松散结合的钙，而其他区室被认为是细胞内钙池。通过在钙洗脱的不同阶段添加该激素，检测血管紧张素II对不同细胞内区室的影响。在洗脱开始时添加血管紧张素，其在1.5分钟内增加了45Ca流出率。然而，当在洗脱第30分钟添加该激素时，这种效应无法检测到，这表明至少一个激素敏感池此时已失去了大部分放射性。与血管紧张素II相反，线粒体解偶联剂FCCP无论在洗脱过程中何时添加，都能动员几乎相同量的45Ca。后一发现表明，这个可能的线粒体钙池交换速率缓慢，因此不同于最初由血管紧张素II动员的池。在含有EGTA的无钙培养基中也观察到了血管紧张素II最初的钙动员效应，这表明这种效应不是由钙内流增加触发的。在本研究中，我们在完整的球状带细胞中证明，血管紧张素II从一个细胞内钙储存中动员钙，该储存似乎与FCCP敏感储存不同。
