ArticlePflugers Archiv : European journal of physiology2005
NH3 and NH4+ permeability in aquaporin-expressing Xenopus oocytes.
Article in Pflugers Archiv : European journal of physiology, 2005. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 98 papers.
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98 citing papers in PubMed, 259 citations in OpenAlex.
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- OsPIP2;4 aquaporin water channel primarily expressed in roots of rice mediates both water and nonselective NaScientific reports · 2025Article
- Urea Transport Mediated by Membrane Proteins of Non-urea-Transporters.Sub-cellular biochemistry · 2025Review
- State of knowledge on ammonia handling by the kidney.Pflugers Archiv : European journal of physiology · 2024Review
- Aquaporins and Ion Channels as Dual Targets in the Design of Novel Glioblastoma Therapeutics to Limit Invasiveness.Cancers · 2023Review
- Transport Characteristics of Aquaporins.Advances in experimental medicine and biology · 2023Article
- Classification and Gene Structure of Aquaporins.Advances in experimental medicine and biology · 2023Article
- The Multifaceted Role of Aquaporin-9 in Health and Its Potential as a Clinical Biomarker.Biomolecules · 2022Review
- Ammonia induces amyloidogenesis in astrocytes by promoting amyloid precursor protein translocation into the endoplasmic reticulum.The Journal of biological chemistry · 2022Article
- Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease.International journal of molecular sciences · 2022Review
- Overexpression of a Cotton Aquaporin GeneInternational journal of molecular sciences · 2022Article
- Astrocytes profiling in acute hepatic encephalopathy: Possible enrolling of glial fibrillary acidic protein, tumor necrosis factor-alpha, inwardly rectifying potassium channel (Kir 4.1) and aquaporin-4 in rat cerebral cortex.Frontiers in cellular neuroscience · 2022Article
- Deciphering the structure, function, expression and regulation of aquaporin-5 in cancer evolution.Oncology letters · 2021Review
- Lsi2: A black box in plant silicon transport.Plant and soil · 2021Review
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- Methyl Jasmonate Affects Photosynthesis Efficiency, Expression ofInternational journal of molecular sciences · 2020Article
- Discovering the RNA-Binding Proteome of Plant Leaves with an Improved RNA Interactome Capture Method.Biomolecules · 2020Article
- Application of the Brown dynamics fluctuation-dissipation theorem to the study of Plasmodium berghei transporter protein PbAQP.Frontiers in physics · 2020Article
38 more citing papers are in PubMed but not listed here.
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Authors and funding
7 authors at 3 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
We have shown recently, in a yeast expression system, that some aquaporins are permeable to ammonia. In the present study, we expressed the mammalian aquaporins AQP8, AQP9, AQP3, AQP1 and a plant aquaporin TIP2;1 in Xenopus oocytes to study the transport of ammonia (NH3) and ammonium (NH4+) under open-circuit and voltage-clamped conditions. TIP2;1 was tested as the wild-type and in a mutated version (tip2;1) in which the water permeability is intact. When AQP8-, AQP9-, AQP3- and TIP2;1-expressing oocytes were placed in a well-stirred bathing medium of low buffer capacity, NH3 permeability was evident from the acidification of the bathing medium; the effects observed with AQP1 and tip2;1 did not exceed that of native oocytes. AQP8, AQP9, AQP3, and TIP2;1 were permeable to larger amides, while AQP1 was not. Under voltage-clamp conditions, given sufficient NH3, AQP8, AQP9, AQP3, and TIP2;1 supported inwards currents carried by NH4+. This conductivity increased as a sigmoid function of external [NH3]: for AQP8 at a bath pH (pH(e)) of 6.5, the conductance was abolished, at pH(e) 7.4 it was half maximal and at pH(e) 7.8 it saturated. NH4+ influx was associated with oocyte swelling. In comparison, native oocytes as well as AQP1 and tip2;1-expressing oocytes showed small currents that were associated with small and even negative volume changes. We conclude that AQP8, AQP9, AQP3, and TIP2;1, apart from being water channels, also support significant fluxes of NH3. These aquaporins could support NH4+ transport and have physiological implications for liver and kidney function.
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