Distinct Effects of Ouabain at Different Concentrations on Rb^+ Uptake in HeLa Cells

概要

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Rb^+ uptake into HeLa cells was investigated in relation to ouabain concentration. The dose-response curve revealed that the glycoside was inhibitory at concentrations above 0.01 μM. The inhibition was saturated at l-10 μM, leaving about 15% of the total Rb^+ uptake behind. Upon incubation with ouabain, Rb^+ uptake was rapidly lowered in 10 min and thereafter it stayed at the level of 15% at least for 1 h. After a replacement of medium K^+ with Rb^+, the sum of intracellular Rb^+ and K^+ contents declined exponentially with time in the presence of 10 μM ouabain. This implies that K^+ or Rb^+ distributes in a single compartment inside the cells. The sum of the both ion contents decreased in the same concentration range of ouabain as shown for Rb^+ uptake. When a higher concentration of ouabain, 100 μM, was applied for 2 h, the ouabain-insensitive Rb^+ uptake increased and the major part of which was furosemidesensitive. Furthermore, a half of the ouabain-insensitive component was ATP-dependent. These changes in the Rb^+ transport system were discussed.
近畿大学の論文
1978-12-28