ISSN:
1432-1912
Keywords:
Neuronal uptake
;
Noradrenaline
;
PC-12 cells
;
Sodium
;
Chloride
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The uptake of 3H-noradrenaline into reserpine-pretreated PC-12 cells (a clonal cell line which possesses “uptake1”) was abolished when at high extracellular Cl−1 all the extracellular Na+ was replaced by Tris+ and when at high extracellular Na+ all the extracellular Cl− was replaced by isethionate. Increases in the external Cl− concentration (at a fixed high Na+ concentration) progressively increased the uptake of 3H-noradrenaline. The same was found with increase in the external Na+ concentration (at a fixed high Cl− concentration). From the anions tested only Br− and SCN− were able to partially mimic the transport-stimulating effect of Cl− (with about 40% and 20% effectiveness, respectively). When chloride was replaced by nitrate or larger anions such as sulphate, methylsulphate or isethionate, virtually no transport of 3H-noradrenaline was observed. The initial rate of uptake of 3H-noradrenaline showed saturation with increasing concentrations of noradrenaline when determined at several fixed concentrations of either Na+ or Cl−. The apparent K m for noradrenaline transport ( $$K_{m_{NA} } $$ ) progressively decreased and the $$V_{max_{NA} } $$ increased with increases in the concentration of Na+ (at a high concentration of Cl−) or Cl− (at a high concentration of Na+). The stimulation of the initial rate of uptake of 3H-noradrenaline by increasing concentrations of either Na+ or Cl− obeyed saturation kinetics when determined at several concentrations of noradrenaline. The concentration of Na+ (or Cl−) which caused half-maximal stimulation of uptake (i.e., the apparent $$K_{m_{Na + } } $$ and the apparent $$K_{m_{Cl - } } $$ ) decreased with increases in the concentration of noradrenaline. These results strongly suggest that Na+ and Cl− are co-transported with noradrenaline.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00512937
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