Kjeldsen K, Nørgaard A, Clausen T
Pflugers Arch. 1985 Aug;404(4):365-73. doi: 10.1007/BF00585350.
The relationship between the number of 3H-ouabain binding sites and the Na, K-pump mediated K-uptake has been characterized in rat soleus muscle. By brief exposure to 3H-ouabain (1 X 10(-6)-1 X 10(-5) mol/l) in vitro, it could be measured that 19-94% of the ouabain binding sites had been occupied. This was associated with a proportionate decrease in the ouabain suppressible K-uptake indicating that under strictly standardized conditions, measurements of 3H-ouabain binding sites quantify functional Na,K-pumps. When 3 week old rats were K-depleted for a further week followed by K-repletion 2 h before measurements, the 3H-ouabain binding site concentration was 61% lower than in age-matched control soleus muscles. However, the ouabain suppressible K-uptake was only reduced by 35%, partly because intracellular Na remained higher in the muscles obtained from K-depleted rats. From the 1st to the 4th week of life, the 3H-ouabain binding site concentration increased 2.9-fold. In contrast, the ouabain suppressible K-uptake decreased by a factor 3.5. Accordingly, in muscles from 1 week old rats, the ouabain suppressible K-uptake per 3H-ouabain binding site was 10-fold higher than in muscles from 4 week old rats. This difference could not be accounted for by changes in intracellular Na, total or extracellular water. It may be related to differentiation and change in structure.(ABSTRACT TRUNCATED AT 250 WORDS)
在大鼠比目鱼肌中，已对3H-哇巴因结合位点数量与钠钾泵介导的钾摄取之间的关系进行了表征。通过在体外短暂暴露于3H-哇巴因（1×10⁻⁶ - 1×10⁻⁵mol/L），可以测得19%-94%的哇巴因结合位点被占据。这与哇巴因可抑制的钾摄取成比例下降相关，表明在严格标准化条件下，对3H-哇巴因结合位点的测量可量化功能性钠钾泵。当3周龄大鼠进一步缺钾一周，然后在测量前2小时补钾时，3H-哇巴因结合位点浓度比年龄匹配的对照比目鱼肌低61%。然而，哇巴因可抑制的钾摄取仅减少了35%，部分原因是缺钾大鼠的肌肉中细胞内钠仍较高。从出生第1周到第4周，3H-哇巴因结合位点浓度增加了2.9倍。相比之下，哇巴因可抑制的钾摄取下降了3.5倍。因此，在1周龄大鼠的肌肉中，每个3H-哇巴因结合位点的哇巴因可抑制钾摄取比4周龄大鼠的肌肉高10倍。这种差异不能用细胞内钠、总体水或细胞外水的变化来解释。它可能与分化和结构变化有关。（摘要截断于250字）
