STIMULATION AND INHIBITION OF THE SODIUM PUMP BY CARDIOACTIVE STEROIDS IN RELATION TO THEIR BINDING SITES AND THEIR INOTROPIC EFFECT ON GUINEA‐PIG ISOLATED ATRIA
STIMULATION AND INHIBITION OF THE SODIUM PUMP BY CARDIOACTIVE STEROIDS IN RELATION TO THEIR BINDING SITES AND THEIR INOTROPIC EFFECT ON GUINEA‐PIG ISOLATED ATRIA
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心脏活性类固醇对钠泵的刺激和抑制与其结合位点及其对豚鼠孤立心房的正性肌力作用
DOI：
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发表时间：
1979
影响因子：
7.3
通讯作者：
T. Godfraind
中科院分区：
文献类型：
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作者：
J. Ghysel‐Burton;T. Godfraind
1在3.3 Hz刺激的豚鼠左心房中研究了哇巴因、哇巴苷元和二氢哇巴因对收缩性和离子含量的作用。已确定哇巴因的特异性结合及其被其他强心内酯取代。2哇巴因或哇巴皂甙元对Na、K含量的作用因浓度不同而有质的差异。低剂量引起Nai的减少，而高剂量产生增加。二氢哇巴因只引起Nai增益。3 KCl浓度从2.7增加到12 mm，未处理心房的Nai降低，哇巴因剂量效应曲线向右移位。4正性肌力作用的ED 50值低于泵抑制的ED 50值，并且不受KCl浓度增加的类似影响。5哇巴因的特异性结合发生在高亲和力位点和低亲和力位点，分别与钠泵激活和抑制有关。6 KCl的增加降低了两组位点对哇巴因的亲和力，并增加了高亲和力位点的容量，而其他位点的容量保持不变。结果证实了哇巴因在豚鼠心脏中存在两个特异性结合位点，并表明抑制Na泵不是强心苷正性肌力作用的唯一机制。
1 The actions of ouabain, ouabagenin and dihydroouabain on the contractility and on the ionic content have been investigated in left guinea‐pig atria stimulated at 3.3 Hz. The specific binding of ouabain and its displacement by the other cardenolides have been determined. 2 The action of either ouabain or ouabagenin on Na and K content was qualitatively different according to the concentration employed. Low doses evoked a reduction of Nai whereas high doses produced an increase. Dihydroouabain evoked only a Nai gain. 3 The increase of KCl concentration from 2.7 to 12 mm decreased Nai in untreated atria and displaced ouabain dose‐effect curves to the right. 4 ED50 values for the positive inotropic effect were lower than ED50 values for the inhibition of the pump and were not similarly affected by an increase in KCl concentration. 5 The specific binding of ouabain occurred at high and low affinity sites, related to Na pump stimulation and inhibition respectively. 6 The increase in KCl reduced the affinity of the two groups of sites for ouabain and increased the capacity of the high‐affinity sites whereas the capacity of the other sites remained unchanged. 7 The results confirm the existence of two specific binding sites for ouabain in guinea‐pig heart and suggest that the inhibition of the Na pump is not the only mechanism responsible for the positive inotropic effect of cardiac glycosides.