Potassium transport in red blood cells of frog Rana temporaria: demonstration of a K?Cl cotransport

Гусев, Г. П.; Agalakova, Natalia I.; Lapin, A. V.

doi:10.1007/bf00260814

Cited by 11 publications

(6 citation statements)

References 33 publications

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“…We showed earlier in frog red blood cells that bumetanide, a selective inhibitor of Na-K-2Cl cotransport, had no effect on K + and Na + transport. In addition the Na + influx is independent of the external K + concentration and of replacement of Cl with NO 3 in the incubation media (Gusev et al, 1995;Agalakova et al, 1996Agalakova et al, , 1997. Moreover, our present experiments provide evidence for similar effects of external Na + concentration on K + loss from frog erythrocytes.…”

Section: Discussionsupporting

confidence: 77%

“…Similar to erythrocytes of other species, the K-Cl cotransporter in frog red cells is significantly activated by cell swelling (Gusev et al, 1995. Therefore, it is important to elucidate the changes in the kinetic properties of K-Cl cotransport following its activation in swollen cells.…”

Section: Effect Of Cell Swelling On K + ( 86 Rb) Influx As a Functionmentioning

confidence: 99%

“…The animals were kept in aquaria at a temperature of 2-4°C. Red blood cells were obtained as reported before (Gusev, Agalakova & Lapin, 1995;Agalakova et al, 1997). Occasionally, blood from two or three frogs was pooled.…”

Section: Cell Preparationmentioning

confidence: 99%

“…Our previous studies (Gusev, Agalakova & Lapin, 1995, 1997 have shown that Cl − -dependent K + transport mediates more than 50% of the total K + fluxes across frog erythrocyte membranes. This Cl − -dependent K + flux is stimulated by cell swelling and most likely represents K-Cl cotransport activity.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of K-Cl Cotransport in Frog Erythrocyte Membrane: Effect of External Sodium

Гусев

Agalakova

Lapin

1999

Journal of Membrane Biology

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In frog red blood cells, K-Cl cotransport (i.e., the difference between ouabain-resistant K fluxes in Cl and NO(3)) has been shown to mediate a large fraction of the total K(+) transport. In the present study, Cl(-)-dependent and Cl(-)-independent K(+) fluxes via frog erythrocyte membranes were investigated as a function of external and internal K(+) ([K(+)](e) and [K(+)](i)) concentration. The dependence of ouabain-resistant Cl(-)-dependent K(+) ((86)Rb) influx on [K(+)](e) over the range 0-20 mm fitted the Michaelis-Menten equation, with an apparent affinity (K(m)) of 8.2 +/- 1.3 mm and maximal velocity (V(max)) of 10.4 +/- 1.6 mmol/l cells/hr under isotonic conditions. Hypotonic stimulation of the Cl(-)-dependent K(+) influx increased both K(m) (12.8 +/- 1.7 mm, P < 0.05) and V(max) (20.2 +/- 2.9 mmol/l/hr, P < 0.001). Raising [K(+)](e) above 20 mm in isotonic media significantly reduced the Cl(-)-dependent K(+) influx due to a reciprocal decrease of the external Na(+) ([Na(+)](e)) concentration below 50 mm. Replacing [Na(+)](e) by NMDG(+) markedly decreased V(max) (3.2 +/- 0.7 mmol/l/hr, P < 0.001) and increased K(m) (15.7 +/- 2.1 mm, P < 0.03) of Cl(-)-dependent K(+) influx. Moreover, NMDG(+) Cl substitution for NaCl in isotonic and hypotonic media containing 10 mm RbCl significantly reduced both Rb(+) uptake and K(+) loss from red cells. Cell swelling did not affect the Na(+)-dependent changes in Rb(+) uptake and K(+) loss. In a nominally K(+)(Rb(+))-free medium, net K(+) loss was reduced after lowering [Na(+)](e) below 50 mm. These results indicate that over 50 mm [Na(+)](e) is required for complete activation of the K-Cl cotransporter. In nystatin-pretreated cells with various intracellular K(+), Cl(-)-dependent K(+) loss in K(+)-free media was a linear function of [K(+)](i), with a rate constant of 0.11 +/- 0.01 and 0.18 +/- 0.008 hr(-1) (P < 0.001) in isotonic and hypotonic media, respectively. Thus K-Cl cotransport in frog erythrocytes exhibits a strong asymmetry with respect to transported K(+) ions. The residual, ouabain-resistant K(+) fluxes in NO(3) were only 5-10% of the total and were well fitted to linear regressions. The rate constants for the residual influxes were not different from those for K(+) effluxes in isotonic ( approximately 0. 014 hr(-1)) and hypotonic ( approximately 0.022 hr(-1)) media, but cell swelling resulted in a significant increase in the rate constants.

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Section: Discussionsupporting

confidence: 77%

Section: Effect Of Cell Swelling On K + ( 86 Rb) Influx As a Functionmentioning

confidence: 99%

Section: Cell Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Kinetics of K-Cl Cotransport in Frog Erythrocyte Membrane: Effect of External Sodium

Гусев

Agalakova

Lapin

1999

Journal of Membrane Biology

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“…The different amounts of vesicles released by Ca# + -loaded erythrocytes in the presence of quinine or ChTX may be due to the different specificities of these inhibitors for the K + channel, or to their interaction with different sites on the channel, or to the effects of quinine on other unknown events relevant to membrane vesiculation. In this respect it is notable that quinine has been observed to inhibit Na + fluxes [42] and phospholipase A and C activity [43,44].…”

Section: Ca 2 + /A23187 Treatment In the Presence Of Chtxmentioning

confidence: 99%

Tyrosine phosphorylation of band 3 protein in Ca2+/A23187-treated human erythrocytes

Minetti

Piccinini

Balduini

et al. 1996

Biochemical Journal

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Human erythrocytes were induced to release membrane vesicles by treatment with Ca2+ and ionophore A23187. In addition to the biochemical changes already known to accompany loading of human erythrocytes with Ca2+, the present study reveals that tyrosine phosphorylation of the anion exchanger band 3 protein also occurs. The relationship between tyrosine phosphorylation of band 3 and membrane vesiculation was analysed using quinine (a non-specific inhibitor of the Ca(2+)-activated K+ channel, and the only known inhibitor of Ca(2+)-induced vesiculation) and charybdotoxin, a specific inhibitor of the apamin-insensitive K(+)-channel. Both inhibitors suppressed tyrosine phosphorylation of band 3. In the presence of quinine, membrane vesiculation was also suppressed. In contrast, at the concentration of charybdotoxin required to suppress tyrosine phosphorylation of band 3, membrane vesiculation was only mildly inhibited (16-23% inhibition), suggesting that tyrosine phosphorylation of band 3 is not necessary for membrane vesiculation. Phosphorylation of band 3 was in fact observed when erythrocytes were induced to shrink in a Ca(2+)-independent manner, e.g. by treatment with the K+ ionophore valinomycin or with hypertonic solutions. These observations suggest that band 3 tyrosine phosphorylation occurs when cell volume regulation is required.

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Regulation of K-Cl Cotransport: from Function to Genes

2004

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This review intends to summarize the vast literature on K-Cl cotransport (COT) regulation from a functional and genetic viewpoint. Special attention has been given to the signaling pathways involved in the transporter's regulation found in several tissues and cell types, and more specifically, in vascular smooth muscle cells (VSMCs). The number of publications on K-Cl COT has been steadily increasing since its discovery at the beginning of the 1980s, with red blood cells (RBCs) from different species (human, sheep, dog, rabbit, guinea pig, turkey, duck, frog, rat, mouse, fish, and lamprey) being the most studied model. Other tissues/cell types under study are brain, kidney, epithelia, muscle/smooth muscle, tumor cells, heart, liver, insect cells, endothelial cells, bone, platelets, thymocytes and Leishmania donovani. One of the salient properties of K-Cl-COT is its activation by cell swelling and its participation in the recovery of cell volume, a process known as regulatory volume decrease (RVD). Activation by thiol modification with N-ethylmaleimide (NEM) has spawned investigations on the redox dependence of K-Cl COT, and is used as a positive control for the operation of the system in many tissues and cells. The most accepted model of K-Cl COT regulation proposes protein kinases and phosphatases linked in a chain of phosphorylation/dephosphorylation events. More recent studies include regulatory pathways involving the phosphatidyl inositol/protein kinase C (PKC)-mediated pathway for regulation by lithium (Li) in low-K sheep red blood cells (LK SRBCs), and the nitric oxide (NO)/cGMP/protein kinase G (PKG) pathway as well as the platelet-derived growth factor (PDGF)-mediated mechanism in VSMCs. Studies on VSM transfected cells containing the PKG catalytic domain demonstrated the participation of this enzyme in K-Cl COT regulation. Commonly used vasodilators activate K-Cl COT in a dose-dependent manner through the NO/cGMP/PKG pathway. Interaction between the cotransporter and the cytoskeleton appears to depend on the cellular origin and experimental conditions. Pathophysiologically, K-Cl COT is altered in sickle cell anemia and neuropathies, and it has also been proposed to play a role in blood pressure control. Four closely related human genes code for KCCs (KCC1-4). Although considerable information is accumulating on tissue distribution, function and pathologies associated with the different isoforms, little is known about the genetic regulation of the KCC genes in terms of transcriptional and post-transcriptional regulation. A few reports indicate that the NO/cGMP/PKG signaling pathway regulates KCC1 and KCC3 mRNA expression in VSMCs at the post-transcriptional level. However, the detailed mechanisms of post-transcriptional regulation of KCC genes and of regulation of KCC2 and KCC4 mRNA expression are unknown. The K-Cl COT field is expected to expand further over the next decades, as new isoforms and/or regulatory pathways are discovered and its implication in health and disease is revealed.

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Potassium transport in red blood cells of frog Rana temporaria: demonstration of a K?Cl cotransport

Cited by 11 publications

References 33 publications

Kinetics of K-Cl Cotransport in Frog Erythrocyte Membrane: Effect of External Sodium

Kinetics of K-Cl Cotransport in Frog Erythrocyte Membrane: Effect of External Sodium

Tyrosine phosphorylation of band 3 protein in Ca2+/A23187-treated human erythrocytes

Regulation of K-Cl Cotransport: from Function to Genes

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