Ion Movements in Red Cells Treated with Propranolol

Ekman, Aarne; Manninen, Vesa; Salminen, Susanna

doi:10.1111/j.1748-1716.1969.tb04386.x

Cited by 42 publications

(15 citation statements)

References 15 publications

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“…Among the three divalent metal ion species known to produce the effect (Ca ++ , Mg + § and Pb + +), only Pb + + is capable of evoking the permeability change in freshly drawn intact cells. Ca §247 acts only if added together with metabolic poisons such as fluoride or iodoacetate plus adenosine (Gardos, 1958(Gardos, , 1959Lepke & Passow, 1960) ; or with certain drugs such as triose reductone (Passow & Vielhauer, 1966) or propranolol (Ekman et al, 1969); or if applied to ghosts (Riordan & Passow, 1971 ;Blum & Hoffman, 1972). Mg § § can replace Ca + + in fluoride poisoning of intact cells, but neither in the Gardos effect [i.e., in the presence of iodoacetate plus adenosine (Lepke & Passow, 1960)] nor in experiments with ghosts (see Table 4).…”

Section: Discussionmentioning

confidence: 99%

Calcium-potassium-stimulated net potassium efflux from human erythrocyte ghosts

et al. 1975

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In the presence of 8 mM external Ca++, the K+ permeability of human red cell ghosts increases provided K+ is also present in the medium. This increase does not represent K+/K+ exchange but a stimulation of net K+ efflux. The stimulation is half-maximal at 0.7 +/- 0.15 mM (n=5). At concentrations above 4.0 mM, external K+ inhibits net K+ efflux. Similar stimulatory and inhibitory effects of external K were also observed in intact cells after exposure to Pb++ or to Ca++ in the presence of fluoride, iodoacetate plus adenosine, or propranolol, suggesting that a common K+ -activated K+ -specific transfer system may be involved under all of these various circumstances. Internal K+ also stimulates net K+ efflux from ghosts, but it is uncertain whether internal K+ is an absolute requirement for the K+ permeability increase. In contrast to external Na+ which slightly stimulates K+ efflux, internal Na+ inhibits. The inhibition by internal Na+ is abolished by sufficiently high concentrations of external K+, showing that K+ binding to the outer membrane surface and Na+ binding to the internal surface are mutually interdependent. In red cell ghosts the Ca++ -K+ -stimulated net K+ efflux increases with increasing pH until a plateau is reached between pH 7.2 and 8.0. In fluoride-poisoned intact cells, the Ca++-K+ stimulated flux passes through a maximum around pH 6.8. Neither internal nor external Mg++ interferes with the combined effects of Ca++ and K+. Similarly, external EDTA has no influence at concentrations which are far lower than the Ca++ concentration required to produce a maximal response. In contrast, low concentrations of internal EDTA prevent the permeability change.

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Section: Discussionmentioning

confidence: 99%

Calcium-potassium-stimulated net potassium efflux from human erythrocyte ghosts

et al. 1975

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“…Our approach was based on the experimental results of Ekman, Manninen and Salminen (1969) as interpreted by Glynn and Warner (1972). According to them the induction of K § efflux into media containing nonpenetrating cations generates a potential which serves as an additional driving force for the influx of labelled cations.…”

Section: Discussionmentioning

confidence: 99%

The use of ionophores of rapid loading of human red cells with radioactive cations for cation-pump studies

1976

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Techniques are described for the rapid loading of intact human red cells with radioactive isotopes of alkali cations or Ca2+ by using ionophorous compounds (nigericin, gramicidin D and A 23187). Loading was rapid and efficient if the membrane potential of the cells was rendered more negative inside. After cation loading the ionophores could be bound to albumin and removed by repeated washings. The ATP and 2,3-DPG contents of the cells were practically unaltered by this treatment. Passive membrane permeability to Na+ and Ca2+ returned to normal. Loaded erythrocytes pumped out Na+ in a ouabain-sensitive and Ca2+ in a lanthanum-sensitive way. Ca2+ -loaded red cells were microspherocytes and exhibited a rapid K+ -efflux. Parallel with the extrusion of Ca2+ cells regained their biconcave shape and normal passive permeability to K+.

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“…The effects of high concentrations of Ca in initiating the slow change would complicate the study of Em when the Gardos effect is induced by adding 10 mM Ca to cells or ghosts depleted of ATP (Kregenow & Hoffman, 1972;Knauf et al, 1975). Propranolol, which has also been used to induce the Gardos effect (Ekman, Manninen & Salminen, 1969), is incompatible with the use of WW 781 because the drug increases the dye fluorescence in the absence of cells. For these reasons, the most convenient way found to study the effect of Ca on E,, of human red cells was to increase [Ca]c by adding the ionophore A 23187 in the presence of controlled amounts of [Ca] o.…”

Section: Time-dependent Changes In Fluorescence and Ementioning

confidence: 99%

Membrane potentials associated with Ca-induced K conductance in human red blood cells: Studies with a fluorescent oxonol dye, WW 781

Freedman

Novak

1983

J. Membrain Biol.

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A divalent anionic dye, bis-[3-methyl-1-p-sulfophenyl-5-pyrazolone-(4)]-pentamethine oxonol (WW 781) is a rapidly responding fluorescent indicator of KCl diffusion potentials induced in human red blood cells with valinomycin, gramicidin, and with the Ca ionophore A 23187 in the presence of external Ca. WW 781 has a sensitivity of 0.13% delta F/mV, a detection limit of 10 mV, a response time of less than 1 sec, and exhibits a decrease in fluorescence intensity upon hyperpolarization without detectable shifts in absorption or emission peaks. This dye does not perturb the normal resting potential, and unlike the slow permeant cyanine dyes, does not inhibit Ca-induced K conductance in human red blood cells. However, WW 781 does stimulate Ca-induced unidirectional Rb efflux. With Ca plus A 23187, the initial rapid change in dye fluorescence is sensitive to [Ca]o and to [A 23187], is reversible with excess EGTA, and is inhibited by quinine, oligomycin, and by trifluoperazine. A biphasic dependence of hyperpolarization on Ko is evident at pH 6, where the ionic selectivity of activation is K, Rb greater than Cs greater than Na and that of conductance is K, Rb greater than Cs. Conditions were defined which permitted continuous monitoring of Em for at least 10 min, and the time dependence of the Ca-induced potentials was characterized. Since the properties of the Ca-induced changes in dye fluorescence correlate well with the known characteristics of Ca-induced K permeability, we conclude that WW 781 is a useful indicator of changes in Em, provided that sufficient controls are employed to separate direct effects of Ca on dye fluorescence from the effects of Em on fluorescence.

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Ion Movements in Red Cells Treated with Propranolol

Cited by 42 publications

References 15 publications

Calcium-potassium-stimulated net potassium efflux from human erythrocyte ghosts

Calcium-potassium-stimulated net potassium efflux from human erythrocyte ghosts

The use of ionophores of rapid loading of human red cells with radioactive cations for cation-pump studies

Membrane potentials associated with Ca-induced K conductance in human red blood cells: Studies with a fluorescent oxonol dye, WW 781

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