Premium
Passive potassium transport in low potassium sheep red cells: dependence upon cell volume and chloride.
Author(s) -
Dunham P B,
Ellory J C
Publication year - 1981
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1981.sp013881
Subject(s) - iodoacetamide , chemistry , potassium , biophysics , ouabain , volume (thermodynamics) , sodium , ion transporter , cell , biochemistry , membrane , biology , enzyme , cysteine , physics , organic chemistry , quantum mechanics
The major pathway of passive K influx (ouabain‐insensitive) was characterized in low‐K type (LK) red cells of sheep. 1. Passive K transport in these cells was highly sensitive to variations in cell volume; it increased threefold or more in cells swollen osmotically by 10%, and decreased up to twofold in cells shrunken 5‐10%. Active K influx was insensitive to changes in cell volume. Three different methods for varying cell volume osmotically all gave similar results. 2. The volume‐sensitive pathway was specific for K in that Na influx did not vary with changes in cell volume. 3. The volume‐sensitive K influx was a saturable function of external K concentration. It was slightly inhibited by Na, whereas K influx in shrunken cells was unaffected by Na. 4. Passive K influx was dependent on the major anion in the medium in that replacement of Cl with any of six other anions resulted in a reduction of K influx by 50‐80% (replacement of Cl by Br caused an increase in K influx). The activation of K influx by Cl followed sigmoid kinetics. 5. Passive K influx is inhibited by anti‐L antibody. The antibody affected only that portion of influx which was Cl‐dependent and volume‐sensitve. Of the subfractions of the antibody, it is anti‐L1 which inhibits passive K transport. 6. Pretreatment of cells with iodoacetamide reduced the sensitivity of K influx to cell volume in that the influx was reduced in swollen IAA‐treated cells and increased in shrunken IAA‐cells. 7. Intracellular Ca has no role in altering passive K transport in LK sheep cells. Therefore, the major pathway of passive K transport in LK sheep red cells is sensitive to changes in cell volume, specific for K, dependent on Cl, and inhibited by anti‐L1 antibody, The minor pathway, observed in shrunken cells, has none of these properties.