Some kinetic and metabolic characteristics of calcium-induced potassium transport in human red cells

• Published in: The Journal of general physiology Vol. 60; no. 4; pp. 406 - 429
• Main Authors: Kregenow, F M, Hoffman, J F
• Format: Journal Article
• Language: English
• Published: United States The Rockefeller University Press 01.10.1972
• Subjects: Adenosine - pharmacology; Adult; Biological Transport; Calcium - metabolism; Calcium - pharmacology; Calcium Isotopes; Cell Membrane Permeability - drug effects; Erythrocytes - drug effects; Erythrocytes - metabolism; Female; Humans; Iodoacetates - pharmacology; Male; Ouabain - pharmacology; Potassium - metabolism; Sodium - metabolism
• ISSN: 0022-1295; 1540-7748
• DOI: 10.1085/jgp.60.4.406

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.