A vacuolar-type proton pump energizes K+/H+ antiport in an animal plasma membrane

Wieczorek, Helmut; Putzenlechner, M.; Zeiske, Wolfgang; Klein, Uwe

doi:10.1016/s0021-9258(18)98621-7

Cited by 286 publications

(34 citation statements)

References 56 publications

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“…As discussed above, the V-ATPase activity seems to be related to transepithelial salt absorption. Thus, after ruling out a major basolateral or intracellular localization for the V-ATPase, it is reasonable to assume that at least a portion of the V-ATPase is located in the apical plasma membrane, as has been proposed for other salt-absorbing (Ehrenfeld et al 1990;Avella and Bornancin, 1990) and salt-secreting (Wieczorek et al 1991;Bertram et al 1991) epithelia. However, more definitive results, for example a co-purification of the V-ATPase with an apical marker enzyme, are needed to support this hypothesis.…”

Section: Discussionmentioning

confidence: 98%

“…Dow, 1992;Gluck and Nelson, 1992), V-ATPases of epithelial plasma membranes have been shown to energize a number of different processes related to the homoeostasis of ions and water in a variety of animals. In the midgut of plant-feeding (high K + load) insect larvae, an apical V-ATPase energizes K + secretion via basolateral K + channels and apical K + /H + antiport (Wieczorek et al 1991;Wieczorek, 1992;Zeiske, 1992;Schirmanns and Zeiske, 1994). Insects counterbalance a salt and water load by secretion across their Malpighian tubule epithelia.…”

Section: Discussionmentioning

confidence: 99%

“…The fluorometric measurements were conducted according to Wieczorek et al (1991) and are described briefly here. For these experiments, we used only the microsomal fraction on top of the 40 % sucrose (M2).…”

Section: Fluorometric Measurementsmentioning

confidence: 99%

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A V-ATPase DRIVES ACTIVE, ELECTROGENIC AND Na+-INDEPENDENT Cl−ABSORPTION ACROSS THE GILLS OF ERIOCHEIR SINENSIS

Onken¹,

Putzenlechner²

1995

Journal of Experimental Biology

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Using biochemical and electrophysiological techniques, we have examined the proposal that an H+-ATPase is involved in Cl- uptake across the gills of the Chinese crab Eriocheir sinensis. Bafilomycin A1 (1 µmol l-1), a specific inhibitor of V-ATPases, was used to investigate the importance of this H+-translocating enzyme in Cl- transport across the gill. In homogenates of ion-transporting posterior gills, we found the activity of a bafilomycin-sensitive V-ATPase to be markedly higher than in the anterior gills, which are not involved in ion transport. A similar distribution was found for the Na+/K+- and the mitochondrial F1Fo-ATPase. After differential and density centrifugation, the specific activity of the V-ATPase was enriched by a factor of 5. Neither Na+/K+- and F1Fo-ATPase activities nor acid phosphatase activity copurified with the bafilomycin-sensitive ATPase activity, indicating that at least the major portion of V-ATPase activity is not of basolateral, mitochondrial or lysosomal origin. In fluorescence studies, using Acridine Orange or Oxonol V as dyes, membrane vesicles displayed ATP-dependent proton transport and membrane potential generation, which were markedly reduced in the presence of bafilomycin. In addition to these biochemical studies, we mounted split lamellae of posterior gills in an Ussing-type chamber and measured the negative short-circuit current (Isc), which was shown to reflect active, electrogenic, Na+-independent and ouabain-insensitive Cl- absorption. After the addition of 1 µmol l-1 bafilomycin to the external bath, this Isc was reduced to about 5060 % of its original value. Concomitantly, the conductance of the preparation decreased by about 13 %. From these results, we conclude that an apical V-ATPase drives electrogenic Cl- uptake across the posterior gills of the Chinese crab.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

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A V-ATPase DRIVES ACTIVE, ELECTROGENIC AND Na+-INDEPENDENT Cl−ABSORPTION ACROSS THE GILLS OF ERIOCHEIR SINENSIS

Onken¹,

Putzenlechner²

1995

Journal of Experimental Biology

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“…An electrophoretic K + /nH + antiporter in the apical membrane could account for the luminal pH of 8, estimated with dyes (M. K. Dasher and W. R. Harvey, unpublished observations) and measured with pH-selective glass microelectrodes (D. Y. Boudko and W. R. Harvey, unpublished observations). The cavity of lepidopteran midgut goblet cells has a near-neutral pH (Chao et al, 1991) even though H + is being transported towards it (Wieczorek et al, 1991; for a review, see Harvey, 1992). In a parallel manner, strong ions in the caecal cavity might be balanced by sulfate ions associated with proteins.…”

Section: Gastric Caecummentioning

confidence: 99%

“…Such an antiporter would alkalize the lumen by exchanging cellular K + for luminal H + . Evidence has been published for such an antiporter in tobacco hornworm larvae (Wieczorek et al, 1991;Azuma et al, 1995) and for a stoichiometrically equivalent Na + /2H + antiporter in alkaliphilic bacteria (Padan and Schuldiner, 1993). The applicability of the antiporter hypothesis to the caterpillar midgut has been challenged on thermodynamic grounds by several authors.…”

Section: Alkalization Mechanismmentioning

confidence: 99%

In Situ Analysis of pH Gradients in Mosquito Larvae Using Non-Invasive, Self-Referencing, pH-Sensitive Microelectrodes

Boudko

Moroz

Linser

et al. 2001

Journal of Experimental Biology

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The alkaline environment, pH approximately 11, in the anterior midgut lumen of mosquito larvae is essential for normal nutrition and development. The mechanism of alkalization is, however, unknown. Although evidence from immunohistochemistry, electron microscopy and electrophysiology suggests that a V-ATPase is present in the basal membranes of the epithelial cells, its physiological role in the alkalization process has not been demonstrated. To investigate a possible role of the V-ATPase in lumen alkalization, pH gradients emanating from the hemolymph side of the midgut in semi-intact mosquito larvae were measured using non-invasive, self-referencing, ion-selective microelectrodes (SERIS). Large H+ concentration gradients, with highest concentrations close to the basal membrane (outward [H+] gradients), were found in the anterior midgut, whereas much smaller gradients, with concentrations lowest close to this membrane (inward [H+] gradients), were found in the gastric caeca and posterior midgut. Similar region-specific pH gradients, with consistent anterior-to-posterior profiles, were observed in individuals of two Aedes species, Aedes aegypti from semi-tropical Florida and Aedes canadensis from north-temperate Massachusetts. The gradients remained in a steady state for up to 6 h, the maximum duration of the recordings. Bafilomycin A1 (10(−5), 10(−7)mol × l(−1)) on the hemolymph side greatly diminished the [H+] gradients in the anterior midgut but had no effect on the gradients in the gastric caecum and posterior midgut. These physiological data are consistent with the previous findings noted above. Together, they support the hypothesis that a basal, electrogenic H+ V-ATPase energizes luminal alkalization in the anterior midgut of larval mosquitoes.

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Ion regulation in the larval lepidopteran midgut and the response toBacillus thuringiensisδ-endotoxin

Gringorten¹

1999

Pestic. Sci.

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Fourth‐instar Bombyx mori (silkworm) was used as a model insect to study the effects of Bacillus thuringiensis (Bt) on ion homeostasis in the larval lepidopteran midgut. The K+ chemical gradient across the midgut of B. mori larvae is quite small, sustained by a lumen/haemolymph activity ratio of only 1.6. More than 95% of the driving force causing K+ flux from lumen to haemolymph is electrical. In contrast to K+, the H+ chemical gradient is exceedingly large, with luminal pH values of 11–12 and haemolymph/lumen H+ ratios as high as 105. At equilibrium, the steep proton gradient is consistent with a passive distribution of H+ across the midgut epithelium as predicted from the Nernst equation. In B mori larvae, ingestion of a lethal dose of Bt δ‐endotoxin produces an increase in K+ conductance in the midgut apical epithelium, causing a decrease in the electrical gradient and dissipation of the pH gradient. Larval morbidity can be correlated with a rise in haemolymph K+ and pH and a decline in luminal pH. Midgut K+ activity, however, remains unchanged. An important factor in the pathogenesis of Bt is irreversible alkalization of the epithelial cells as H+ is redistributed across the midgut to reach a new Nernst equilibrium.

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A vacuolar-type proton pump energizes K+/H+ antiport in an animal plasma membrane

Cited by 286 publications

References 56 publications

A V-ATPase DRIVES ACTIVE, ELECTROGENIC AND Na+-INDEPENDENT Cl−ABSORPTION ACROSS THE GILLS OF ERIOCHEIR SINENSIS

A V-ATPase DRIVES ACTIVE, ELECTROGENIC AND Na+-INDEPENDENT Cl−ABSORPTION ACROSS THE GILLS OF ERIOCHEIR SINENSIS

In Situ Analysis of pH Gradients in Mosquito Larvae Using Non-Invasive, Self-Referencing, pH-Sensitive Microelectrodes

Ion regulation in the larval lepidopteran midgut and the response toBacillus thuringiensisδ-endotoxin

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