Some kinetic and metabolic characteristics of calcium-induced potassium transport in human red cells.
When fresh human erythrocytes or their ghosts are incubated with Ca + IAA (iodoacetic acid) + adenosine, K permeability increases; K permeability also increases when energy-depleted cells or their ghosts are incubated with Ca alone. Na transport decreases or remains unaltered in both situations. The Ca-induced increase in K permeability in the depleted cell system is qualitatively similar to that seen in the fresh cell system and furnishes a means for studying the metabolic dependence of calcium's action. Studies with the depleted system suggest that the normal refractiveness of the cell to calcium is provided by a metabolically dependent substrate. Removal of this substrate allows Ca to enter the cell and exert its effect. By using (47)Ca, a maximum value was obtained (3-7 x 10(-6) moles/liter of red blood cells) for the quantity of calcium that is taken up by the cell and responsible for the change in K permeability. Measurements of the unidirectional fluxes of K, obtained during the time Ca increases K permeability, appear to satisfy the flux ratio equation for passive diffusion through a membrane.
D000241:Adenosine / Q000494:pharmacology; D000328:Adult; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002127:Calcium Isotopes; D002463:Cell Membrane Permeability / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D007461:Iodoacetates / Q000494:pharmacology; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism
D002127:Calcium Isotopes; D007461:Iodoacetates; D010042:Ouabain; D012964:Sodium; D000241:Adenosine; D011188:Potassium; D002118:Calcium