We studied pH regulation in freshly isolated rainbow trout hepatocytes using microspectrofluorometry with the fluorescent dye BCECF. In accordance with earlier data on rainbow trout hepatocytes, ion substitution (N-methyl D-glucamine for sodium and gluconate for chloride) and transport inhibitor [10 microM M methyl isobutyl amiloride (MIA) to inhibit sodium/proton exchange and 100 microM DIDS to inhibit bicarbonate transport] studies in either Hepes-buffered or bicarbonate/carbon dioxide-buffered media (extracellular pH 7.6) indicated a role for sodium/proton exchange, sodium-dependent bicarbonate transport, and sodium-independent anion exchange in the regulation of hepatocyte pH. In Hepes-buffered medium, the activity of the sodium/proton exchanger (i.e. proton extrusion inhibited by MIA) was greater at 1% than at 21% oxygen. The oxygen dependency of the sodium/proton exchange is not caused by hydroxyl radicals, which appear to mediate the oxygen sensitivity of potassium-chloride cotransport in erythrocytes.
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Ther Apher Dial
January 2025
Division of Nephrology, Endocrinology, and Metabolism, Department of Internal Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
Patients on dialysis often develop hyperphosphatemia, contributing to an increased risk of cardiovascular events and mortality. Currently, several types of phosphate binders (PBs) exist for the treatment of hyperphosphatemia, but they are sometimes associated with drug-specific side effects and high pill burden, making it difficult to control serum phosphorus appropriately. Tenapanor, which has a novel mechanism to reduce serum phosphorus via selective sodium/proton exchange transporter 3 inhibition, was approved for hyperphosphatemia in Japan in 2023.
View Article and Find Full Text PDFNature
January 2025
Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Increasing soil salinity causes significant crop losses globally; therefore, understanding plant responses to salt (sodium) stress is of high importance. Plants avoid sodium toxicity through subcellular compartmentation by intricate processes involving a high level of elemental interdependence. Current technologies to visualize sodium, in particular, together with other elements, are either indirect or lack in resolution.
View Article and Find Full Text PDFJ Biol Chem
December 2024
Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan, USA. Electronic address:
Endocytosis is a prominent mechanism for SARS-CoV-2 entry into host cells. Upon internalization into early endosomes (EEs), the virus is transported to late endosomes (LEs), where acidic conditions facilitate spike protein processing and viral genome release. Dynein and kinesin motors drive EE transport along microtubules; dynein moves EEs to the perinuclear region, while kinesins direct them towards the plasma membrane, creating a tug-of-war over the direction of transport.
View Article and Find Full Text PDFPLoS Biol
December 2024
School of Biosciences, University of Sheffield, Western Bank, Sheffield, United Kingdom.
The interaction between cancer cells and the extracellular matrix (ECM) plays a pivotal role in tumour progression. While the extracellular degradation of ECM proteins has been well characterised, ECM endocytosis and its impact on cancer cell progression, migration, and metastasis is poorly understood. ECM internalisation is increased in invasive breast cancer cells, suggesting it may support invasiveness.
View Article and Find Full Text PDFAndrology
December 2024
Faculty of Medicine, Department of Obstetrics, Gynecology and Reproduction, Centre Hospitalier Universitaire de Québec - Research Centre, and Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle - Université Laval, Québec, QC, Canada.
Introduction: The epididymis creates an optimal acidic luminal environment for sperm maturation and storage. In epididymal principal cells (PCs), proton secretion is activated by the accumulation of the sodium-proton exchanger type 3, NHE3 (SLC9A3), in apical stereocilia. PCs also secrete ATP, which is hydrolyzed into adenosine by ectonucleotidases.
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