Absence of KCNQ1-dependent K+ fluxes in proximal tubular cells of frog kidney. 2007

Dusan Cemerikic, and Jelena Nesovic-Ostojic, and Dusan Popadic, and Aleksandra Knezevic, and Simon Dragovic, and Aleksandar Milovanovic, and Jovica Milovanovic
Department of Pathological Physiology, Medical Faculty, Dr Subotica 1/II, 11000 Belgrade, Serbia. dcemeri@afrodita.rcub.bg.ac.yu

The present study was designed to investigate the functional significance of KCNQ1-mediated K+ secretory fluxes in proximal tubular cells of the frog kidney. To this end, we investigated the effects on rapid depolarization and slow repolarization of the peritubular membrane potential after luminal addition of L-phenylalanine or L-alanine plus/minus KCNQ1 channel blockers. Perfusing the lumen with 10 mmol/L L-phenylalanine plus/minus luminal 293B, a specific blocker of KCNQ1, did not modify the rapid depolarization and the rate of slow repolarization. Perfusing the lumen with 10 mmol/L L-alanine plus/minus luminal HMR-1556, a more potent KCNQ1 channel blocker, did not also alter the rapid depolarization and the rate of slow repolarization. Pretreatment (1 h) of the lumen with HMR-1556 also failed to modify rapid depolarization and rate of slow repolarization upon luminal 10 mmol/L L-alanine. Perfusing the lumen with 1 mmol/L L-alanine plus/minus luminal HMR-1556 did not change the rapid depolarization and the rate of slow repolarization. The pretreatment (1 h) with luminal HMR-1556 did not modify the rapid depolarization and the rate of slow repolarization upon luminal 1 mmol/L L-alanine. The pretreatment (1 h) of the lumen with HMR-1556 did not change transference number for K+ of peritubular cell membrane. Finally, luminal barium blunted the rapid depolarization upon application of luminal 1 mmol/L L-alanine. RT-PCR showed that KCNQ1 mRNA was not expressed in frog kidney. In conclusion, the KCNQ1-dependent K+ secretory fluxes are absent in proximal tubule of frog kidney.

UI MeSH Term Description Entries
D007687 Kidney Tubules, Proximal The renal tubule portion that extends from the BOWMAN CAPSULE in the KIDNEY CORTEX into the KIDNEY MEDULLA. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the U-shaped LOOP OF HENLE. Proximal Kidney Tubule,Proximal Renal Tubule,Kidney Tubule, Proximal,Proximal Kidney Tubules,Proximal Renal Tubules,Renal Tubule, Proximal,Renal Tubules, Proximal,Tubule, Proximal Kidney,Tubule, Proximal Renal,Tubules, Proximal Kidney,Tubules, Proximal Renal
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008564 Membrane Potentials The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization). Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D010477 Perfusion Treatment process involving the injection of fluid into an organ or tissue. Perfusions
D010649 Phenylalanine An essential aromatic amino acid that is a precursor of MELANIN; DOPAMINE; noradrenalin (NOREPINEPHRINE), and THYROXINE. Endorphenyl,L-Phenylalanine,Phenylalanine, L-Isomer,L-Isomer Phenylalanine,Phenylalanine, L Isomer
D011188 Potassium An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011893 Rana esculenta An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog". Pelophylax esculentus
D002839 Chromans Benzopyrans saturated in the 2 and 3 positions. Dihydrobenzopyrans
D000409 Alanine A non-essential amino acid that occurs in high levels in its free state in plasma. It is produced from pyruvate by transamination. It is involved in sugar and acid metabolism, increases IMMUNITY, and provides energy for muscle tissue, BRAIN, and the CENTRAL NERVOUS SYSTEM. Abufène,Alanine, L-Isomer,L-Alanine,Alanine, L Isomer,L Alanine,L-Isomer Alanine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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