title: A transient sodium-hydrogen exchange system induced by catecholamines in erythrocytes of rainbow trout, Salmo gairdneri.
abstract: The addition of isoprenaline to an isotonic suspension of red blood cells of rainbow trout induces an amiloride-sensitive Na+ transport which is independent of Cl- and insensitive to 4,4'-diisothiocyano-2,2'-stilbene disulphonic acid (DIDS) and furosemide. Na+ uptake is accompanied by amiloride-sensitive H+ release. The H+ efflux is dependent upon the external Na+ concentration, the K0.5 value for Na+ being 16 mM. In the presence of DIDS, when the coupled NaCl entry (NaCl co-transport) induced by catecholamine is blocked, the results provide evidence for a linked movement of Na+ and H+, with a stoicheiometry of 1:1. Exchange of H+ for Na+ induces osmotic swelling of the cells which is due to the replacement of a bound proton by an osmotically active Na+ cation. In the absence of DIDS when the bulk of the Na+ uptake is the result of a coupled entry of Na+ and Cl-, H+ extrusion still occurs and the magnitude of acid excretion is identical to that found in DIDS-treated cells. This suggests that Na+-H+ exchange remains active. Addition of isoprenaline first stimulates the Na+-H+ exchange but only transiently. This is followed by a more permanent stimulation of the NaCl co-transport.
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006859:Hydrogen / Q000097:blood*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D009997:Osmotic Pressure; D012487:Salmonidae / Q000097:blood*; D012964:Sodium / Q000097:blood*; D014337:Trout / Q000097:blood*
chemical_list: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D007545:Isoproterenol; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid