Anion transport in dog, cat, and human red cells. Effects of varying cell volume and Donnan ratio.
Castranova-V; Weise-MJ; Hoffman-JF
J Gen Physiol 1979 Sep; 74(3):319-334
The influence of cell volume and membrane potential on anion transport in red blood cells was studied in-vitro. Red blood cells isolated from venous blood obtained from dogs, cats, and human donors were preloaded with sulfur-35 (S-35) labeled sulfate ion (SO4- 2) or chloride-36 (Cl-36) labeled chloride ion (Cl-) or placed in a medium containing radiolabeled SO4-2 or Cl-. The volume of the cells was altered by placing them in a medium containing 0 to 200 millimolar sucrose. In some experiments the cells were pretreated with nystatin to alter their membrane potential. Other cells were incubated in a medium without glucose to deplete them of energy. SO4-2 or Cl- transport was determined by measuring the rate constants for efflux and influx of S-35 and Cl-36. Cell membrane potentials were calculated from equilibrium anion distribution ratios or determined by a fluorescence technique. In dog and cat erythrocytes the rate of efflux of SO4-2 and Cl- was increased by either cell shrinkage or swelling. SO4-2 influx was also decreased by either shrinkage or swelling. In human erythrocytes cellular swelling increased SO4-2 efflux and cell shrinkage decreased SO4-2 efflux. Membrane potentials in human cells became more negative as the cells swelled and more positive as they shrank. The membrane potential of dog red cells became more negative for either shrinkage or swelling. When human cells were pretreated with nystatin that maintained the membrane potential at a constant value, the rate of SO4-2 efflux was relatively unchanged for cell volume changes of up to 40 percent. Varying membrane potentials by +12.5 millivolts but keeping cell volume constant resulted in a 5O percent decrease in Cl- efflux. Energy depleted cat and dog erythrocytes showed a volume dependence of membrane potential and SO4-2 efflux that was very similar to that of human cells. The authors conclude that the changes in anion transport of red blood cells accompanying changes in cellular volume reflect changes in membrane potential.
NIOSH-Author; Red-blood-cells; In-vitro-studies; Humans; Laboratory-animals; Bioelectric-effects; Ionization; Cellular-structures
Journal of General Physiology