Adam W R, Koretsky A P, Weiner M W
Department of Medicine, Veterans Administration Medical Center, San Francisco 94121.
Am J Physiol. 1988 Mar;254(3 Pt 2):F401-6. doi: 10.1152/ajprenal.1988.254.3.F401.
To investigate the effects of K+ uptake on the intracellular environment, both 39K-nuclear magnetic resonance (NMR) and K+-selective electrodes were used to measure K+ activity with acute K+ loading in control and K+-adapted rats. These results were then compared with tissue K+, measured by flame photometry. There was a lower NMR K+ visibility (ratio of NMR signal to tissue content) in muscle and liver in K+-adapted rats, compared with controls before and after an acute K+ load. This lower K+ visibility in K+-adapted rats was confirmed in liver homogenate with the K+-specific electrode. In liver homogenates from control and K+-adapted rats, addition of RbCl (300 mumol/g) increased the NMR K+ signal more in K+-adapted rats (19 +/- 1.1 mumol/g) than controls (11 +/- 1.0 mumol/g, P less than 0.01). This is consistent with the displacement of K+, by Rb+, from NMR-undetected sites. These results suggest that some 10-15% of intracellular K+ may be within a compartment not detectable by NMR or electrodes and that chronic K+ loading leads to an increased capacity of this compartment.
为了研究钾离子摄取对细胞内环境的影响，采用³⁹K核磁共振（NMR）和钾离子选择性电极，在对照大鼠和适应钾离子的大鼠中，通过急性钾离子负荷来测量钾离子活性。然后将这些结果与通过火焰光度法测量的组织钾离子含量进行比较。与急性钾离子负荷前后的对照大鼠相比，适应钾离子的大鼠肌肉和肝脏中的核磁共振钾离子可见度（核磁共振信号与组织含量的比值）较低。在肝脏匀浆中使用钾离子特异性电极证实了适应钾离子的大鼠中这种较低的钾离子可见度。在对照大鼠和适应钾离子的大鼠的肝脏匀浆中，添加氯化铷（300 μmol/g）后，适应钾离子的大鼠（19 ± 1.1 μmol/g）的核磁共振钾离子信号增加幅度比对照大鼠（11 ± 1.0 μmol/g，P < 0.01）更大。这与铷离子从核磁共振检测不到的位点置换钾离子的情况一致。这些结果表明，约10% - 15%的细胞内钾离子可能存在于核磁共振或电极检测不到的隔室中，并且慢性钾离子负荷会导致该隔室的容量增加。
