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F Aull

Publications and source records attributed to F Aull.

13 recordsLinked to original sources
PubMed1982

Specific drug sensitive transport pathways for chloride and potassium ions in steady-state Ehrlich mouse ascites tumor cells.

A major aim of this investigation was to determine whether, in steady-state ascites cells, Cl- transport can be partitioned into a furosemide-sensitive cotransport with K+ and a separate 4,4'-isothiocyanostilbene-2,2'-disulfonic acid (DIDS) sensitive self-exchange. Both Cl- and K+ fluxes were studied. The furosemide- and Cl- sensitive K+ fluxes were equivalent, both in normal ionic media and when the external K+ concentration, [K+]o, was varied from 4 to 30 mM. The stoichiometry of the furosemide-sensitive Cl- and K+ fluxes was 2 Cl-:1 K+ at 0.1 and 0.5 mM drug levels but increased to 3 Cl-:1 K+ at 1.0 mM furosemide. DIDS at 0.1 mM had no effect on the K+ exchange rate but inhibited Cl- exchange by 39% +/- 2 (S.E.). The effects of DIDS and 0.5 mM furosemide on Cl- transport were additive but 1.0 mM furosemide and DIDS had overlapping inhibitory actions. Thus furosemide acts on components of K+ and Cl- transport which are linked to each other, but the drug also inhibits an additional DIDS-sensitive Cl- pathway, when present at higher concentrations. The dependence of the furosemide-sensitive K+ and Cl- transport on [K+]o was also studied; both fluxes fell as the [K+]o increased. The latter results recall those in an earlier study by Hempling (Hempling, H.G. (1962) J. Cell. Comp. Physiol. 60, 181-198).

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1981

Potassium chloride cotransport in steady-state ascites tumor cells. Does bumetanide inhibit?

Bumetanide is a potent diuretic drug which has some structural features in common with furosemide. The steady-state exchange of K+ and Cl- was investigated in Ehrlich ascites tumor cells treated with bumetanide. This agent did not alter the cellular content of K+ or Cl- but the self-exchange of both ions was depressed. K+ self-exchange was inhibited by 55% at bumetanide concentrations as low as 10(-6) M. Cl- self-exchange was less sensitive to this drug but at low concentrations (between 10(-6) and 10(-3) M) bumetanide was a more effective inhibitor of Cl- transfer than furosemide. The steady-state K+ flux of cells equilibrated in NO3- media was compared with the K+ flux in cells treated with 10(-4) or 10(-3) M bumetanide; the Cl(-)-sensitive K+ exchange was equivalent to the bumetanide-sensitive K+ exchange. Since the results suggested that a bumetanide-sensitive (Cl-, K+) cotransport could be operative in steady-state cells, the stoichiometry of the bumetanide-sensitive fluxes was determined by measuring Cl- and K+ fluxes simultaneously in the same cell suspension. At 5 . 10(-4) and 10(-3) M bumetanide concentrations, the ratio of these fluxes was 0.98 +/- 0.07 (S.E.) and 1.04 +/- 0.06, respectively, consistent with the postulated cotransport mechanism. At 10(-4) and 10(-5) M, however, the ratio of the bumetanide-sensitive Cl-/K+ flux was significantly less than 1.0. Since the magnitude of the bumetanide-sensitive K+ flux at 10(-4) M was close to that of the Cl(-)-sensitive flux, a ratio of less than 1.0 at this drug level indicates that Cl-sensitivity and drug sensitivity may not reflect inhibition of the same process under all circumstances.

Animals↗
PubMed1980

Inhibition of Ehrlich ascites cell anion transport by 1-isothiocyanate-4-benzenesulfonic acid.

The effects of 1-isothiocyanate-4-benzene sulfonic acid on steady state Cl- and SO24(4 transport in Ehrlich mouse ascites tumor cells were investigated. At 10 mM, 1-isothiocyanate-4-benzenesulfonic acid reduced SO24(-) exchange by 94% but Cl- exchange was reduced by only 37%; Cl- exchange was not further inhibited by as much as 60 min of preincubation with 1-isothiocyanate-4-benzenesulfonic acid. Inhibition of Cl- exchange was completely reversible following 30-45 min of contact with 1-isothiocyanate-4-benzenesulfonic acid whereas under the same conditions, inhibition of SO24(-) exchange was irreversible. The effect o 1-isothiocyanate-4-benzenesulfonic acid on SO24(-) transport could be reversed, however, when exposure to 1-isothiocyanate-4-benzene-sulfonic acid lasted for only 2 min. In these respects the action of 1-isothiocyanate-4-benzenesulfonic acid resembles that of 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid and 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid; the results are compatible with separate membrane sites for Cl- and SO24(-) transport. The Ki for reversible inhibition of SO24(-) transport, determined from a Dixon plot, was 4.8 mM and the inhibition appeared to be non-competitive.

Animals↗
PubMed1979

Saturation behavior of ascites tumor cell chloride exchange in the presence of gluconate.

Steady state Cl- flux across the Ehrlich mouse ascites cell membrane was studied when gluconate replaced Cl- in the external medium. Saturation behavior was observed; K 1/2 was 23.9 mM Cl- and V was 758 micromol.g-1 dry weight.h-1. The cells lost K+, Cl- and H2O, consistent with relative impermeability to gluconate, and the Cl- efflux rate coefficient was elevated. The results indicate that a major portion of Cl- exchange occurs as a membrane transport process and suggest that the process is sensitive to intracellular Cl- levels.

Animals↗
PubMed1977

Chloride self exchange in Ehrlich ascites cells. Inhibition by furosemide and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid.

The effects of furosemide and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) on steady-state Cl- flux were studied in Ehrlich mouse ascites cells. At 10 mM, furosemide inhibited isotopically-determined Cl- flux by 86% without changing cell Cl- content, indicating that influx and efflux were depressed by the same amount. These results suggest that at least 86% of the steady-state Cl- flux may occur as a one for one exchange. Half of the inhibitory effect was not reversed by vigorous washing with albumin-Ringer. A smaller portion of steady-state Cl- flux was inhibited by SITS. The maximum effect of SITS was reached near 0.6 mM; at this concentration Cl- flux was reduced by 37% without an alteration in cell Cl- content. Possible competition of environment Cl- and SITS was investigated by replacing environment Cl- with acetate or NO3. These anions reduced the efficacy of SITS because they depressed cell Cl- turnover themselves, apparently acting on the same exchange process.

Animals↗
PubMed1977

Nature of lectin-induced alteration of potassium transfer in Ehrlich ascites tumor cells.

The way in which the lectins concanavalin A (Con A) and Ricinus communis agglutinin (Ricin) alter the K+ content of Ehrlich ascites tumor cells was investigated. Unidrectional and net fluxes were determined in unwashed cells during a time course following lectin addition. Total influx, ouabain sensitive influx, Mg++- and Na+-K+-ATPase activity were all unaffected. Cell ATP content was normal for at least 19 minutes after exposure to Con A. Early after contact with Ricin or Con A efflux was stimulated 2-3-fold, resulting in net K+ loss, but after 20 minutes efflux had returned to normal. Ricin and Con A acted similarly although Ricin was present at only 1/50 the concentration of Con A. When the findings are evaluated together with previous work it is suggested that a particular membrane glycoprotein may be concerned in the efflux alteration observed.

Adenosine Triphosphatases↗
PubMed1976

Interactions of lectins with plasma membrane glycoproteins of the Ehrlich ascites carcinoma cell.

Several aspects of the interaction of various lectins with the surface of Ehrlich ascites carcinoma cells are described. The order of agglutinating activity for various lectins is Ricinus communis greater than wheat germ greater than or equal to concanavalin A greater than or equal to soybean greater than Limulus polyphemus. No agglutination was noted for Ulex europaeus. Using 125I-labeled lectins it was determined that there are 1.6 and 7 times as many Ricinus communis lectin binding sites for concanavalin A and soybean lectins. Sodium deoxycholate-solubilized plasma membrane material was subjected to lectin affinity chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The lectin receptors of the plasma membrane appeared to be heterogeneous and some qualitative differences could be discerned among the electrophoretically analyzed material, which bound to and was specifically eluted from the various lectin affinity columns. The characteristics of elution of bound material from individual lectin columns indicated secondary hydrophobic interactions between concanavalin A or wheat germ agglutinin and their respective lectin receptor molecules.

Adenosine Triphosphatases↗
PubMed1972

The effect of external anions on steady-state chloride exchange across ascites tumour cells.

1. The rate of cell chloride exchange, or efflux coefficient, was measured after equilibration in media of different anionic composition.2. When sulphate substituted for chloride in the medium, the efflux coefficient was always higher than in control chloride solutions and varied inversely with external chloride concentration. In sulphate the chloride efflux coefficient varied from 19.6 to 100.7 hr(-1). The mean control efflux coefficient was 6.60 +/- 0.677 (S.E. of mean).3. In contrast, when external nitrate substituted for chloride, the efflux coefficient was independent of external chloride concentration and the same as in control chloride media. The mean value in nitrate was 6.42 +/- 0.603 (S.E. of mean). The results confirm findings of Hempling & Kromphardt (1965).4. Steady-state chloride flux varied in direct proportion to the external chloride concentration, which would be expected for passive chloride exchange. However, the slope of the line relating these variables was higher in sulphate than in nitrate and control media. Thus at any given external chloride concentration chloride flux was greater in sulphate than in nitrate and control solutions.5. It is suggested that the effect of sulphate to increase cell chloride exchange may be related to its greater tendency to bind water, relative to chloride and nitrate.

Animals↗