Volume and anion dependency of ouabain-resistant K-Rb fluxes in sheep red blood cells.
The effect of six different anions on the volume response of ouabain-resistant K transport was systematically studied at extracellular pH (pHo) = 7.4 in sheep red blood cells of both low and high K genotype before and after treatment with the sulfhydryl (SH) reagent N-ethylmaleimide (NEM). In methanesulfonate (CH3SO3), both the apparent Rb permeability (P(app)Rb), calculated from ouabain-resistant Rb influx), and K permeability (PK, calculated from the rate constants of ouabain-resistant zero-trans K efflux, 0k(OR)K) were volume independent and close to 10(-10) cm/s for both cell types, but in Cl, Br, I, SCN, and NO3 they were significantly different in low and high K cells with altered cell volumes. Thus, in 15% osmotically shrunken low K cells, P(app)Rb) and PK were similar regardless of the anions present, but upon 10-15% swelling, they increased to approximately 4-6 X 10(-9) cm/s in Br and 2 X 10(-9) cm/s in Cl and also increased with comparatively small increments in I, SCN, and NO3. Treatment with NEM enhanced both P(app)Rb) and PK, particularly in shrunken low K cells, to approximately 10(-8) cm/s in Br and Cl but not in I, SCN, and NO3. In shrunken or isotonic high K cells, P(app)Rb) and PK were close to 10(-10) cm/s in all anions except for SCN. Swelling and/or NEM increased PK and P(app)Rb) in Cl and Br only two- to threefold.(ABSTRACT TRUNCATED AT 250 WORDS)
Lauf
P K
PK
Department of Physiology and Biophysics, School of Medicine, Wright State University, Dayton, Ohio 43401-0927.
D000818:Animals; D000838:Anions; D004351:Drug Resistance; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000097:blood*; D012413:Rubidium / Q000097:blood*; D012756:Sheep
D000838:Anions; D010042:Ouabain; D012413:Rubidium; D011188:Potassium