Johnson W T, Dufault S N
United States Department of Agriculture, Grand Forks Human Nutrition Research Center, ND 58202.
Biochim Biophys Acta. 1993 Feb 17;1175(3):263-8. doi: 10.1016/0167-4889(93)90215-b.
The influence of copper deficiency on the mobilization of Ca2+ from intracellular stores following ionomycin treatment or thrombin activation of rat platelets was examined using the fluorescent indicator, fura-2, to measure changes in cytosolic Ca2+ concentration ([Ca2+]i). Platelets, obtained from copper-deficient and control rats and loaded with fura-2, were suspended in medium containing 1 mM EGTA and no added Ca2+. The size of the internal Ca2+ pools in the suspended platelets was estimated from the rise in [Ca2+]i following maximal discharge of stored Ca2+ by treatment with 1 microM ionomycin. Peak [Ca2+]i following ionomycin treatment was lower in platelets from copper-deficient rats compared to control rats (148 +/- 27 nM vs. 188 +/- 17 nM), suggesting that the size of the Ca2+ storage pools was decreased by copper deficiency. Furthermore, once internal Ca2+ stores were discharged by ionomycin, [Ca2+]i remained elevated in platelets from copper-deficient rats, but decreased in control rats. These data indicate that copper deficiency may inhibit the efflux of Ca2+ from platelets after its release from internal stores by ionomycin treatment. In platelets from copper-deficient and control rats, stimulation with 0.1 U/ml thrombin led to rapid rise followed by a slow decay in [Ca2+]i. However, peak [Ca2+]i was lower in platelets from copper-deficient rats than in control rats (94 +/- 19 nM vs. 131 +/- 16 nM). These findings imply that by reducing the amount of Ca2+ available for release from intracellular stores, copper deficiency also reduces [Ca2+]i following thrombin activation in the absence of external Ca2+.
利用荧光指示剂fura - 2检测细胞溶质Ca2 +浓度（[Ca2 +]i）的变化，研究了铜缺乏对离子霉素处理或凝血酶激活大鼠血小板后细胞内钙库中Ca2 +动员的影响。从缺铜大鼠和对照大鼠获取并加载fura - 2的血小板悬浮于含1 mM乙二醇双乙醚二胺四乙酸（EGTA）且未添加Ca2 +的培养基中。通过用1 microM离子霉素处理使储存的Ca2 +最大程度释放后，根据[Ca2 +]i的升高来估计悬浮血小板中内部钙库的大小。与对照大鼠相比，缺铜大鼠的血小板经离子霉素处理后的[Ca2 +]i峰值较低（148±27 nM对188±17 nM），表明铜缺乏使Ca2 +储存池的大小减小。此外，一旦离子霉素使内部钙库释放，缺铜大鼠血小板中的[Ca2 +]i仍保持升高，而对照大鼠的则下降。这些数据表明，铜缺乏可能抑制离子霉素处理使Ca2 +从内部储存释放后血小板中Ca2 +的外流。在缺铜大鼠和对照大鼠的血小板中，用0.1 U/ml凝血酶刺激导致[Ca2 +]i迅速升高，随后缓慢下降。然而，缺铜大鼠血小板中的[Ca2 +]i峰值低于对照大鼠（94±19 nM对131±16 nM）。这些发现表明，通过减少可从细胞内储存释放的Ca2 +量，铜缺乏在无外部Ca2 +的情况下也会降低凝血酶激活后的[Ca2 +]i。
