Mechanisms of cobalt(II) uptake into V79 Chinese hamster cells

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Abstract
V79 Chinese hamster cells were used as a model for the characterization of the Co(II) uptake into mammalian cells as well as the mechanisms involved. Co(II) was taken up in a dose and time dependent manner. The uptake was exponential without saturation in the tested concentration range up to 400 μM. CoCl2. Furthermore, there was a high intracellular cobalt accumulation at elevated extra-cellular Co(II) doses (up to 16 fold at 200 μM). The time course of Co(II) uptake showed a maximum after about 8–12 h with no further change after the longest tested incubation time (24 h). The uptake of Co(II) into V79 cells seems to be mediated by multiple mechanisms: active, energy consuming transport like ion pumps and endocytosis, since the Co(II) uptake was significantly reduced by ouabain (an inhibitor of the Na+/K+ATPase), N-ethyl-maleinimide (an inhibitor of the Ca2+/Mg2+ATPase and the Na+/K+ATPase), chlorpromazine (a calmodulin antagonist and inhibitor of the Ca2+/Mg2+ ATPase) as well as by the endocytosis inhibitor chloroquine. Furthermore, the two agents iodoacetate and potassium cyanide, which produce ATP depletion, resulted in a diminution of the intracellular cobalt concentration. An uptake through anion channels could be excluded, since 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid was not inhibitory