Acceleration of sodium-calcium exchange activity during ATP-induced calcium release in transfected Chinese hamster ovary cells.
Acceleration of sodium-calcium exchange activity during ATP-induced calcium release in transfected Chinese hamster ovary cells.
复制标题
转染的中国仓鼠卵巢细胞中 ATP 诱导的钙释放过程中钠钙交换活性的加速。
DOI：
10.1085/jgp.109.1.53
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Reeves,JP
中科院分区：
文献类型：
--
作者：
Vázquez,M;Fang,Y;Reeves,JP
P2U嘌呤能激动剂ATP （0.3 mM）在转染的表达牛心脏Na/Ca2交换剂（CK1）的中国仓鼠卵巢细胞内释放Ca2，从而引起[Ca2] i的增加。4细胞)。以下观察结果表明，ATP诱导的Ca2释放伴随着Ca2依赖性的Na/Ca2交换活性的调节激活：在ATP后0-1分钟内加入细胞外Ca2(0.7 mM)，与含Na培养基相比，无Na培养基（Li替代）中的[Ca2] i显著升高；载体转染的细胞在na基和li基培养基中无差异。在细胞外Na和Ca2生理浓度存在的情况下，atp引起的[Ca2] i升高在CK1中下降得更快。4个细胞与对照细胞相比，但随后达到了一个长期的[Ca2] i升高的平台，最终超过了对照细胞中下降的[Ca2] i值。ATP引起交换介导的Ba2内流的短暂加速，与Na/Ca2交换的调节激活一致。在载体转染的对照细胞或CK1中未观察到Ba2内流的加速。4细胞在缺乏细胞内Na或当细胞内储存的Ca2含量被先前的离子霉素治疗降低。蛋白激酶C激活剂phorbol 12-肉豆蔻酸酯13-乙酸酯在无na条件下减弱了交换介导的[Ca2] i升高，但没有抑制atp引起的Ba2内流刺激。因此，PMA的作用不是由于交换活性的抑制，而可能反映了蛋白激酶C对其他Ca2稳态机制的影响。我们得出结论，通过增加[Ca2] i的调节激活，在atp诱导的细胞内Ca2释放过程中，交换活性加速。在没有细胞外Ca2的情况下，交换活性的刺激是短暂的，并且遵循[Ca2] i的时间过程是短暂的；在细胞外Ca2存在的情况下，我们认为交换器在更长的时间内保持激活状态，从而稳定和延长存储依赖性Ca2进入的平台期。
From the Department of Physiology, Pharmacology and Toxicology, University of Medicine and Dentistry of New Jersey, The New Jersey Medical School, Newark, New Jersey 07103 abstract The P2U purinergic agonist ATP (0.3 mM) elicited an increase in [Ca2] i due to Ca2 release from intracellular stores in transfected Chinese hamster ovary cells that express the bovine cardiac Na/Ca2 exchanger (CK1. 4 cells). The following observations indicate that ATP-evoked Ca2 release was accompanied by a Ca2-dependent regulatory activation of Na/Ca2 exchange activity: Addition of extracellular Ca2(0.7 mM) 0–1 min after ATP evoked a dramatic rise in [Ca2] i in Na-free media (Li substitution) compared to Na-containing media; no differences between Na-and Li-based media were observed with vector-transfected cells. In the presence of physiological concentrations of extracellular Na and Ca2, the ATP-evoked rise in [Ca2] i declined more rapidly in CK1. 4 cells compared to control cells, but then attained a long-lived plateau of elevated [Ca2] i which eventually came to exceed the declining [Ca2] i values in control cells. ATP elicited a transient acceleration of exchange-mediated Ba2 influx, consistent with regulatory activation of the Na/Ca2 exchanger. The acceleration of Ba2 influx was not observed in vector-transfected control cells, or in CK1. 4 cells in the absence of intracellular Na or when the Ca2 content of the intracellular stores had been reduced by prior treatment with ionomycin. The protein kinase C activator phorbol 12-myristate 13-acetate attenuated the exchange-mediated rise in [Ca2] i under Na-free conditions, but did not inhibit the ATP-evoked stimulation of Ba2 influx. The effects of PMA are therefore not due to inhibition of exchange activity, but probably reflect the influence of protein kinase C on other Ca2 homeostatic mechanisms. We conclude that exchange activity is accelerated during ATP-evoked Ca2 release from intracellular stores through regulatory activation by increased [Ca2] i. In the absence of extracellular Ca2, the stimulation of exchange activity is short-lived and follows the time course of the [Ca2] i transient; in the presence of extracellular Ca2, we suggest that the exchanger remains activated for a longer period of time, thereby stabilizing and prolonging the plateau phase of store-dependent Ca2 entry.