Fish red blood cells: characteristics and physiological role of the membrane ion transporters.
Several membrane ion transporters playing a role in gas transport and exchanges, cell volume regulation and intracellular acid-base regulation have been identified in fish red blood cells (RBCs). This short review focuses on Na+/K+ATPase and its role in establishing the ionic gradients across the membrane, on the Cl-/HCO3- exchanger and its key role in respiration and possibly in inducing a chloride conductance, on the Na+/H+ exchanger and the recent advances on its molecular mechanisms of activation and regulation, on the different types of K-Cl cotransports, the different hypotheses and suggested models and their role in cell volume regulation. There is no evidence in the literature for ionic channels in fish RBCs. We present original data obtained with the patch-clamp technique that shows for the first time the existence of a DIDS-sensitive chloride anionic conductance measured in whole cell configuration and the presence of a stretch-activated nonselective cationic channel recorded in cell-attached and excised inside-out configuration. The part played by these ionic conductances is discussed in relation with their possible involvement in volume regulation.
Thomas
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CNRS, Unité de Recherche en Physiologie Cellulaire, Université de Bretagne Occidentale, Brest, France. serge.thomas@univ-brest.fr
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D000818:Animals; D017920:Antiporters / Q000502:physiology; D002352:Carrier Proteins / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D027963:Chloride-Bicarbonate Antiporters; D004912:Erythrocytes / Q000378:metabolism / Q000502:physiology*; D005399:Fishes / Q000097:blood*; D007477:Ions; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology; D027981:Symporters; D000096922:K Cl- Cotransporters
D017920:Antiporters; D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D007477:Ions; D017923:Sodium-Hydrogen Exchangers; D000254:Sodium-Potassium-Exchanging ATPase; D027981:Symporters; D000096922:K Cl- Cotransporters