Volume-activated cation transport in dog red cells: detection and transduction of the volume stimulus.
1. Carnivore red cells lose their Na/K pump capability as they develop from erythroblasts to reticulocytes to mature cells. They defend their fluid volume by utilizing the Ca/Na exchanger as a Na extrusion pump, the energy for which is ultimately derived from active Ca transport. 2. Swelling-induced [K-Cl] cotransport and shrinkage-induced Na/H exchange are regulated in a coordinated fashion in dog red cells. Circumstantial evidence points to a regulatory protein kinase-phosphatase system. 3. Dog red cells detect changes in their fluid volume, not by virtue of membrane distortion, but by alterations in the concentrations of cytoplasmic macromolecules induced by swelling or shrinkage.
Department of Medicine, University of North Carolina, Chapel Hill 27599-7035.
J C
JC
Parker
D000818:Animals; D001692:Biological Transport; D001693:Biological Transport, Active; D002412:Cations / Q000097:blood*; D004285:Dogs; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D015398:Signal Transduction; D012964:Sodium / Q000097:blood
D002412:Cations; D012964:Sodium