Differential effects of general anesthetics on the quaternary structure of the Ca-ATPases of cardiac and skeletal sarcoplasmic reticulum.
Differential effects of general anesthetics on the quaternary structure of the Ca-ATPases of cardiac and skeletal sarcoplasmic reticulum.
复制标题
全身麻醉药对心脏和骨骼肌浆网 Ca-ATP 酶四级结构的不同影响。
DOI：
10.1021/bi9722002
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Thomas,DD
中科院分区：
文献类型：
--
作者：
Kutchai,H;Geddis,LM;Jones,LR;Thomas,DD
研究了已醇、氟烷和乙醚对心肌和骨骼肌肌浆网(SR)Ca-ATPase活性和低聚体状态的影响。这些全麻药对心脏和骨骼肌中Ca-ATPase活性的影响相似，表现为低浓度时对Ca-ATPase活性有刺激作用，而高浓度时则表现为抑制作用。用异硫氰酸红素(ERITC)或碘乙酰胺(ERIA)共价标记的SR的时间分辨磷光各向异性(TPA)衰变来估计Ca-ATPase在其低聚体中的分布。与Ca-ATPase活性的相似反应相反，心脏SR和骨骼SR对全麻药引起的TPA衰减的反应有显著差异。在心脏中，正己醇、氟烷和乙醚在很长时间内导致极限各向异性显著增加(r∞)，这表明在实验的毫秒时间尺度上太大而不能旋转的低聚物的比例增加。相比之下，在骨骼肌中，∞对三种全麻药的反应没有显著变化。心脏和骨骼SR对全身麻醉药反应的这种差异并不是由于心脏SR中存在磷蛋白，而是因为来自AT-1细胞的SR对类似于心脏SR的全身麻醉药的反应有INR∞增加。AT-1细胞的SR具有SERCA2a亚型的Ca-ATP酶，但只有微量的磷蛋白。用ERIA标记心脏SR的实验给出了类似的结果，表明ERITC的结果不是标记过程的人工产物。在对照条件下，增加LiCl的离子强度可减少心肌细胞Ca-ATPase大分子不活动寡聚体的比例，但可增加对己醇反应的大分子寡聚体的形成。
The effects of the general anesthetics hexanol, halothane, and diethyl ether on Ca-ATPase activity and on the oligomeric state of the Ca-ATPase of sarcoplasmic reticulum (SR) from cardiac and skeletal muscle were investigated. The effects of these general anesthetics on Ca-ATPase activity were similar in cardiac and skeletal SR and were characterized by stimulation of Ca-ATPase activity at lower concentrations of anesthetics and inhibition at higher concentrations. The distribution of the Ca-ATPase among its oligomeric states was estimated from the time-resolved phosphorescence anisotropy (TPA) decay of SR in which Ca-ATPase was covalently labeled with erythrosin isothiocyanate (ERITC) or with erythrosin iodoacetamide (ERIA). In contrast to the similar responses of Ca-ATPase activity, there were marked differences in the responses to general anesthetics of the TPA decay between cardiac and skeletal SR. IncardiacSR hexanol, halothane, and diethyl ether caused pronounced increases in the limiting anisotropy at very long times (r∞), which indicate increases in the fraction of oligomers too large to rotate on the millisecond time scale of the experiments. InskeletalSR, by contrast, there were no significant changes inr∞in response to the three general anesthetics. This difference between cardiac and skeletal SR in response to general anesthetics is not due to the presence of phospholamban in cardiac SR, since SR from AT-1 cells, which have the SERCA2a isoform of Ca-ATPase, but only trace levels of phospholamban, have increases inr∞in response to the general anesthetics that resemble those in cardiac SR. Experiments with cardiac SR labeled with ERIA give similar results, showing that the results with ERITC are not an artifact of the labeling procedure. Increasing the ionic strength with LiCl diminished the proportion of large immobile oligomers of cardiac Ca-ATPase under control conditions but enhanced the formation of large oligomers in response to hexanol.