Volume-dependent K+ transport in rabbit red blood cells comparison with oxygenated human SS cells.
In this study the volume-dependent or N-ethylmaleimide (NEM)-stimulated, ouabain-insensitive K+ influx and efflux were measured with the tracer 86Rb+ in rabbit red blood cells. The purpose of the work was to examine the rabbit as a potential model for cell volume regulation in human SS red blood cells and also to investigate the relationship between the NEM-reactive sulfhydryl group(s) and the signal by which cell swelling activates the transport. Ouabain-resistant K+ efflux and influx increase nearly threefold in cells swollen hypotonically by 15%. Pretreatment with 2 mM NEM stimulates efflux 5-fold and influx 10-fold (each measured in an isotonic medium). The ouabain-resistant K+ efflux was dependent on the major anion in the medium. The anion dependence of K+ efflux in swollen or NEM-stimulated cells was as follows: Br- greater than Cl- much greater than NO3- = acetate. The magnitudes of both the swelling- and the NEM-stimulated fluxes are much higher in young cells (density separated but excluding reticulocytes) than in older cells. Swelling- or NEM-stimulated K+ efflux in rabbit red blood cells was inhibited 50% by 1 mM furosemide, and the inhibitory potency of furosemide was enhanced by extracellular K+, as is known to be true for human AA and low-K+ sheep red blood cells. The swelling-stimulated flux in both rabbit and human SS cells has a pH optimum at approximately 7.4. We conclude that rabbit red blood cells are a good model for swelling-stimulated K+ transport in human SS cells.(ABSTRACT TRUNCATED AT 250 WORDS)
al-Rohil
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Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550.
Jennings
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ML
D000755:Anemia, Sickle Cell / Q000097:blood*; D000818:Animals; D000838:Anions; D001692:Biological Transport; D002712:Chlorides / Q000097:blood; D004195:Disease Models, Animal; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005033:Ethylmaleimide / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011188:Potassium / Q000097:blood*; D011817:Rabbits; D012414:Rubidium Radioisotopes / Q000097:blood; D012964:Sodium / Q000097:blood
D000838:Anions; D002712:Chlorides; D012414:Rubidium Radioisotopes; D005665:Furosemide; D012964:Sodium; D005033:Ethylmaleimide; D011188:Potassium