The effects of ryanodine on passive calcium fluxes across sarcoplasmic reticulum membranes.
The effects of ryanodine on passive calcium fluxes across sarcoplasmic reticulum membranes.
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DOI：
10.1016/s0021-9258(18)61565-0
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发表时间：
1987-02
期刊：
影响因子：
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通讯作者：
F. Lattanzio;Robert;Schlattererl;Michael Nicart;Kevin;Campbell;John L. SutkoSQII
中科院分区：
文献类型：
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作者：
F. Lattanzio;Robert;Schlattererl;Michael Nicart;Kevin;Campbell;John L. SutkoSQII
Ryanodine在0.01-10 μ M的浓度增加，而10-300 μ M的更高浓度降低兔快收缩骨骼肌交界处和犬心肌肌浆网膜的钙渗透性。Ryanodine没有改变肌浆网膜或钙结合蛋白，钙螯合蛋白的钙结合。因此，该药物的作用似乎仅涉及膜通透性的变化，受兰尼定影响的钙通透性途径的特征是钙释放通道的特征。与此一致，ryanodine的作用局限于连接肌浆网膜，而在纵肌浆网膜或横小管膜上均未观察到。此外，连接肌浆网膜通过French press并没有减弱ryanodine的作用，表明不需要完整的三联体。在用于渗透性研究的条件下，[3 H]ryanodine与骨骼肌连接肌浆网膜的结合是特异性和饱和的，Scatchard分析表明存在单个结合位点，Kd为150-200 nM，最大容量为10.1-18.9 pmol/mg蛋白。[3 H]ryanodine与该位点的结合和低浓度ryanodine引起的膜钙渗透性增加具有相似的特征，表明该位点的作用产生这种效应。根据所用的试验条件，ryanodine（100-300 μ M）可以增加或减少骨骼肌连接肌浆网膜ATP依赖性钙积累，表明该药物引起的肌浆网膜钙渗透性的改变可以部分由实验环境决定。
Ryanodine at concentrations of 0.01-10 microM increased, while greater concentrations of 10-300 microM decreased the calcium permeability of both rabbit fast twitch skeletal muscle junctional and canine cardiac sarcoplasmic reticulum membranes. Ryanodine did not alter calcium binding by either sarcoplasmic reticulum membranes or the calcium binding protein, calsequestrin. Therefore, the effects by this agent appear to involve only changes in membrane permeability, and the characteristics of the calcium permeability pathway affected by ryanodine were those of the calcium release channel. Consistent with this, the actions by ryanodine were localized to junctional sarcoplasmic reticulum membranes and were not observed with either longitudinal sarcoplasmic reticulum or transverse tubular membranes. In addition, passage of the junctional sarcoplasmic reticulum membranes through a French press did not diminish the effects of ryanodine indicating that intact triads were not required. Under the conditions used for the permeability studies, the binding of [3H]ryanodine to skeletal junctional sarcoplasmic reticulum membranes was specific and saturable, and Scatchard analyses indicated the presence of a single binding site with a Kd of 150-200 nM and a maximum capacity of 10.1-18.9 pmol/mg protein. [3H]ryanodine binding to this site and the increase in membrane calcium permeability caused by low concentrations of ryanodine had similar characteristics suggesting that actions at this site produce this effect. Depending on the assay conditions used, ryanodine (100-300 microM) could either increase or decrease ATP-dependent calcium accumulation by skeletal muscle junctional sarcoplasmic reticulum membranes indicating that the alterations of sarcoplasmic reticulum membrane calcium permeability caused by this agent can be determined in part by the experimental environment.