title: The effect of abnormal hemoglobins on the membrane regulation of cell hydration.
abstract: Several hemoglobinopathies are associated with abnormalities in the permeability of the red cell membrane, in some cases leading to permanent alterations of the intracellular milieu. Homozygous sickle cell disease is the most thoroughly studied example. Deoxygenation of sickle cells causes a transient increase in the permeability to monovalent cations and Ca; prolonged deoxygenation can lead to a permanent accumulation of Ca and loss of total cations and water. Although the mechanisms for the permeability changes are not yet defined, mechanical stress on the membrane, with subsequent damages by excess Ca or membrane-associated hemoglobin have been suggested to play a role. Loss of cell water and increase in mean cell hemoglobin concentration causes massive reduction of cell deformability in the oxygenated state and makes the hemoglobin more likely to undergo sickling because of the strong concentration dependence of the sickling process. Limited evidence suggests the occurrence of permeability defects in other hemoglobinopathies and the thalassemias. The suggested alterations range from a slight increase in K permeability of incubated thalassemia cells to substantial dehydration of cells from patients with homozygous hemoglobin C disease. Oxidative damage to the membrane, involving an abnormal hemoglobin-membrane association, may underly the permeability changes in these cells.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000755:Anemia, Sickle Cell / Q000097:blood; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability; D004905:Erythrocyte Aging; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D004913:Erythrocytes, Abnormal / Q000378:metabolism; D006455:Hemoglobins, Abnormal / Q000378:metabolism*; D006801:Humans; D011188:Potassium / Q000378:metabolism; D013789:Thalassemia / Q000097:blood; D014867:Water / Q000378:metabolism*
chemical_list: D006455:Hemoglobins, Abnormal; D014867:Water; D000255:Adenosine Triphosphate; D011188:Potassium; D002118:Calcium