Evidence for proteic water pathways in the luminal membrane of kidney proximal tubule

Pratz, J.; Ripoche, Pierre; Corman, B.

doi:10.1016/0005-2736(86)90035-0

Cited by 40 publications

(19 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the present time, we cannot conclude with any certainty that the water channels in aspen are sensitive to temperature; nevertheless, the results suggest that the mercury-sensitive processes are also temperature sensitive. If the effect of HgCl 2 is mainly on water channels, as reported for individual cells and isolated membrane vesicles (Macey, 1984;Meyer and Verkman, 1987;Pratz et al, 1986;Maurel et al, 1997;Niemietz and Tyerman, 1997), then the channels may indeed be temperature sensitive. However, we cannot exclude the possibility that other, temperature-sensitive processes involved in root water transport are affected by mercury resulting in this effect.…”

Section: Discussionmentioning

confidence: 86%

“…Mercury reversibly inhibits the bulk water transport across membranes in animal cells (Pratz et al, 1986;Meyer and Verkman, 1987) and plant cells (Maggio and Joly, 1995;Carvajal et al, 1996;Maurel et al, 1997;Niemietz and Tyerman, 1997). This reversible inhibition is used to demonstrate the existence of proteinaceous water channels (Chrispeels and Maurel, 1994).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Mercuric Chloride Effects on Root Water Transport in Aspen Seedlings

1999

View full text Add to dashboard Cite

HgCl 2 (0.1 mM) reduced pressure-induced water flux and root hydraulic conductivity in the roots of 1-year-old aspen (Populus tremuloides Michx.) seedlings by about 50%. The inhibition was reversed with 50 mM mercaptoethanol. Mercurial treatment reduced the activation energy of water transport in the roots from 10.82 ؎ 0.700 kcal mol ؊1 to 6.67 ؎ 0.193 kcal mol ؊1 when measured over the 4°C to 25°C temperature range. An increase in rhodamine B concentration in the xylem sap of mercury-treated roots suggested a decrease in the symplastic transport of water. However, the apoplastic pathway in both control and mercurytreated roots constituted only a small fraction of the total root water transport. Electrical conductivity and osmotic potentials of the expressed xylem sap suggested that 0.1 mM HgCl 2 and temperature changes over the 4°C to 25°C range did not induce cell membrane leakage. The 0.1 mM HgCl 2 solution applied as a root drench severely reduced stomatal conductance in intact plants, and this reduction was partly reversed by 50 mM mercaptoethanol. In excised shoots, 0.1 mM HgCl 2 did not affect stomatal conductance, suggesting that the signal that triggered stomatal closure originated in the roots. We suggest that mercury-sensitive processes in aspen roots play a significant role in regulating plant water balance by their effects on root hydraulic conductivity.Several criteria have been used to infer the presence of water-transporting channels in cell membranes. These include a high ratio of osmotic to diffusional water permeability (P f /P d Ͼ1), low Arrhenius activation energy (E a Ͻ 6 kcal mol Ϫ1 ) for water transport, and its reversible inhibition by mercury sulfhydryl reagents (for reviews, see Chrispeels and Agre, 1994;Verkman et al., 1996;Maurel, 1997). The transport of water through the lipid bilayer has a high E a , usually above 10 kcal mol Ϫ1 (Macey, 1984). Water transport can also be via water channel proteins (aquaporins), which have been found in the tonoplasts (Maurel et al., 1993) and plasma membranes (Kammerloher et al., 1994) of plants. It is generally acknowledged that the transport of water via channels is less temperature dependent and has a lower E a (Ͻ 6 kcal mol Ϫ1 ) than transport via the lipid pathway (Finkelstein, 1987;Chrispeels and Agre, 1994). Water transport via aquaporins is characteristically inhibited by mercurial reagents, which react with sulfhydryl groups in the channel proteins and result in closure of the channels. This closure inhibits water transport and increases E a to the level of that for transport through the lipid pathway (Macey, 1984). An inhibition of water transport by mercury was reported in cell membranes isolated from higher plants Niemietz and Tyerman, 1997) and in whole root systems (Maggio and Joly, 1995;Carvajal et al., 1996). However, the effects of mercury reagents on E a have not been investigated in intact higher plants.Based on the composite transport model (Steudle and Frensch, 1996), water transport is via three parallel pathways, apoplastic, ...

show abstract

Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Mercuric Chloride Effects on Root Water Transport in Aspen Seedlings

1999

View full text Add to dashboard Cite

show abstract

“…Thus, the effect of Hg2+ on the osmotic relations of the root tissues analyzed here appears to be minimal. We also note that the concentration of HgC1, used here was lower than that used in recent studies of mercurial effects on water channel function (Pratz et al, 1986;Preston et al, 1992;Daniels et al, 1994).…”

Section: Discussionmentioning

confidence: 86%

“…Some aquaporins have been localized exclusively in roots (Yamamoto et al, 1991) or in seeds (Hofte et al, 1992); in either case, they may influence the movement and partitioning of water among neighboring cells. The use of mercurial sulfhydryl reagents as specific water channel inhibitors has been widely reported (Macey, 1984;Pratz et al, 1986;Meyer and Verkman, 1987), and subsequent addition of an excess of ME has been used to remove Hg from membranes of treated cells or tissues. Such studies have provided strong evidence of a proteinmediated pathway for water movement through membranes of certain mammalian and amphibian cell types (van Hoek et al, 1990;Preston et al, 1992;Maurel et al, 1993).…”

mentioning

confidence: 99%

Effects of Mercuric Chloride on the Hydraulic Conductivity of Tomato Root Systems (Evidence for a Channel-Mediated Water Pathway)

1995

View full text Add to dashboard Cite

A pressure-flux approach was used to evaluate the effects of HgCI, on water transport in tomato (Lycopersicon esculentum) roots. Addition of HgCI, to a root-bathing solution caused a large and rapid reduction in pressure-induced root water flux; the inhibition was largely reversible upon addition of P-mercaptoethanol. Root system hydraulic conductivity was reduced by 57%. There was no difference between treatments in the K+ concentration in xylem exudate. The results are consistent with the presence of a proteinmediated path for transmembrane water flow in tomato roots.

show abstract

“…(3 NaCl has the same osmotic effects as mannitol (Zeuthen, 1991), which has a reflection coefficient of one across cell membranes. 0TNaC1 has been recorded to be close to one in membrane vesicles from proximal tubules (Pearce & Verkman, 1989; Van der Goot, Podevin & Corman, 1989) and from small intestine (van Heeswijk & van 0s, 1986), but about 0'5 in isolated, non-perfused proximal tubules (Welling, Welling & Ochs, 1987) and in vesicles from rat kidney brush border (Pratz, Ripoche & Corman, 1986). Obviously there is a need to compare the experimental conditions of the various rapports.…”

Section: Discussionmentioning

confidence: 95%

Secondary active transport of water across ventricular cell membrane of choroid plexus epithelium of Necturus maculosus.

Zeuthen

1991

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. The interaction between Cl-, K+ and H20 fluxes were studied in the ventricular membrane of the choroid plexus epithelium from Necturu8s macUlosus by means of ion-selective microelectrodes. The flux of H20 was measured by means of K+ electrodes as the dilution or concentration of intracellular choline ions, Cht.2. In one series of experiments Cl-was readministered to the ventricular solution of tissues incubated in media with low Cl-concentrations. The resulting influx of Clwas associated with an instantaneous influx of K+ and H20.3. Both the C1-and the K+ influxes were reduced by the diuretic furosemide but were unaffected by inhibitors of Na+, K+-ATPase or changes in membrane potentials induced by Ba2 . Since the influx of K+ proceeds against its electrochemical gradient and is unaffected by changes in membrane potentials, the membrane exhibits secondary active, electroneutral transport of K+.4. The influx of water, initiated simultaneously with the influx of K+ and Cl-, commenced before these ions had changed the osmolarity of the intracellular solution significantly. The influx of H20 could proceed against an osmotic gradient. The influx stopped when 100 mmol 11 of mannitol was added to the ventricular solution at the same time as the Cl-ions. The influx of H20 was inhibited by K+ removal, furosemide or high external Ba2+ (10 mmol 1-1), but not by strophanthidin, ouabain or low concentrations of Ba2+ (0-5 mmol 1-1). The influx could not continue with other permeable anions, N03-, acetate-or SCN-, replacing Cl-.5. In another series of experiments Cl-was removed from the ventricular solution of tissues bathed in saline solutions with normal concentrations of Cl-. The resulting efflux of Cl-was associated with an instantaneous efflux of K+ and H20. This efflux of H20 could proceed against an osmotic gradient of up to 70 mosmol 1-1. This effect was inhibited by furosemide, in which case the water fluxes were entirely dependent on the osmotic gradients and the osmotic water permeability Lp of the ventricular membrane.6. The data suggest that there is a coupling between the flux of KCI and of water in the ventricular membrane, which implies that the reflection coefficient oC for KCI under the given circumstances is less than one. I suggest that the ability of leaky epithelia to transport against osmotic gradients depends on such a coupling, which Ms 8844 derives from the properties of the proteins through which K+, C1-and H20 leave the cell.

show abstract

Evidence for proteic water pathways in the luminal membrane of kidney proximal tubule

Cited by 40 publications

References 17 publications

Mercuric Chloride Effects on Root Water Transport in Aspen Seedlings

Mercuric Chloride Effects on Root Water Transport in Aspen Seedlings

Effects of Mercuric Chloride on the Hydraulic Conductivity of Tomato Root Systems (Evidence for a Channel-Mediated Water Pathway)

Secondary active transport of water across ventricular cell membrane of choroid plexus epithelium of Necturus maculosus.

Contact Info

Product

Resources

About