A study of releasable Ca fractions in smooth muscle cells of the rabbit aorta.
A study of releasable Ca fractions in smooth muscle cells of the rabbit aorta.
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DOI：
10.1085/jgp.69.4.401
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发表时间：
1977-04
影响因子：
3.8
通讯作者：
Casteels, R
中科院分区：
文献类型：
--
作者：
Deth, R;Casteels, R
通过分析去甲肾上腺素、咖啡因和DNP对~（45）Ca交换和张力发展模式的影响，研究了Ca在兔主动脉平滑肌细胞细胞室中的分布。这三种物质增加了组织中45 Ca的释放，但DNP的作用比去甲肾上腺素或咖啡因慢。此外，去甲肾上腺素和咖啡因对紧张局势的发展的影响几乎立即发生，而DNP出现后，只有延迟5分钟。研究这些物质对钙外流的影响表明，去甲肾上腺素和咖啡因的行为可能在同一个钙室，而DNP似乎作用于不同的车厢，以较慢的交换率。这两个池之间的差异可以通过研究在富含K的溶液或具有降低的[Ca]o的溶液中用示踪剂加载组织后的Ca释放来进一步证明。K去极化导致细胞45 Ca过度负荷。暴露这些细胞在流出过程中的解决方案，含有DNP导致更大的释放45 Ca比后观察到的加载程序在正常的解决方案。相反，去甲肾上腺素或咖啡因在这些组织中引起的45 Ca释放消失。这种消失是由于K去极化引起的Ca交换量的长期增加。在初始暴露于PSS期间，增加的交换导致示踪剂从去甲肾上腺素和咖啡因作用的组织隔室加速损失，而DNP敏感隔室不受影响。这表明，去甲肾上腺素和咖啡因作用于同一钙池接近膜和DNP主要作用于线粒体。
The distribution of Ca in the cellular compartment of smooth muscle cells of the rabbit aorta has been studied by analyzing the effect of norepinephrine, caffeine, and DNP on 45Ca exchange and on the pattern of tension development. These three substances increase the release of 45Ca from the tissue, but DNP acts more slowly than norepinephrine or caffeine. Also, the effect of norepinephrine and caffeine on tension development occurs almost immediately, while that of DNP appears only after a delay of 5 min. Study of the effect of these substances on the Ca efflux has shown that norepinephrine and caffeine act probably on the same Ca compartment, while DNP seems to act on a different compartment with a slower exchange rate. The difference between these two pools could be further demonstrated by studying Ca release after loading the tissues with tracer in either K-rich solution or in a solution with reduced [Ca]o. The K depolarization results in an excessive loading of the cells with 45Ca. Exposing these cells during the efflux procedure to a solution containing DNP causes a much larger release of 45Ca than that observed after a loading procedure in normal solution. In contrast, the release of 45Ca elicited in such tissues by norepinephrine or caffeine disappears. This disappearance is due to the prolonged increase of the Ca exchangeability induced by K depolarization. During initial exposure to PSS the increased exchangeability causes an accelerated loss of tracer from the tissue compartment on which norepinephrine and caffeine act, while the DNP sensitive compartment is not affected. It is suggested that noradrenaline and caffeine act on the same calcium pool close to the membrane and that DNP acts mainly on the mitochondria.