The influence of pH and membrane potential on passive Na+ and K+ fluxes in human red blood cells

• Published in: Biochimica et biophysica acta Vol. 886; no. 3; p. 373
• Main Authors: Chipperfield, A R, Shennan, D B
• Format: Journal Article
• Language: English
• Published: Netherlands 29-05-1986
• Subjects: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid - analogs & derivatives; 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid - pharmacology; Adult; Anions - blood; Bumetanide - blood; Erythrocytes - metabolism; Humans; Hydrogen-Ion Concentration; Mathematics; Membrane Potentials; Ouabain - pharmacology; Potassium - blood; Sodium - blood; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors; Sodium-Potassium-Exchanging ATPase - metabolism; Sulfonamides - pharmacology
• ISSN: 0006-3002
• DOI: 10.1016/0167-4889(86)90172-2

Passive (ouabain-insensitive) Na+ and K+ effluxes from human red blood cells were measured over the range pHo 6.2-8.5. On raising pHo, Na+ efflux increased and this was mainly attributable to the piretanide-sensitive component: K+ efflux likewise but attributable to both piretanide-sensitive and piretanide-insensitive components. On replacing Cl- with non-penetrating anions (mainly gluconate), Na+ and K+ effluxes increased, mostly attributable to the piretanide-insensitive components. On restoring pHi either by reducing pHo or by applying DIDS, the influence of pHo on Na+ and K+ effluxes was diminished. These results suggest that pHi rather than Em is the dominant influence. Passive Na+ and K+ effluxes and influxes in the presence of bumetanide were tested fro conformity to the Ussing independence relationship. For K+, the calculated and observed ratios agreed, indicating that the sodium pump, 'cotransport' and leak wholly account for K+ fluxes in human red blood cells. For Na+, the ratios did not agree and a 1:1 Na+/Na+ exchange did not account for the discrepancy. Pathways for Na+ appear to be more numerous than for K+.