Biomaterial Database

On the nature of delayed repolarization during sustained sodium coupled transport in frog proximal tubules. 1987

W Rehwald, and F Lang

Institute for Medical Physics, University of Innsbruck, Austria.

In proximal tubules of the frog kidney, stimulation of coupled transport of sodium with phenylalanine leads to depolarization of the cell membrane, followed by repolarization within a few minutes. The repolarization is due to a delayed increase of potassium conductance at the peritubular cell membrane. The present study was designed to test for the role of depolarization, of calmodulin and of arachidonic acid metabolites for the delayed increase of potassium conductance. To this end, the potential difference across the peritubular cell membrane of proximal convoluted tubules (PDpt) has been recorded continuously during exposure of the lumen to phenylalanine or during galvanic current injection into a neighbouring cell. During control conditions, PDpt averages -68.6 +/- 1.0 mV (n = 45). Phenylalanine leads to a depolarization of the peritubular cell membrane by +31.5 +/- 1.3 mV (n = 20), followed by a repolarization by -12.9 +/- 1.1 mV (n = 20) within 3 min. Injection of currents from 10 to 80 nAmps leads to a depolarization by +0.83 +/- 0.01 mV/nAmps which is again followed by repolarization. A linear correlation is observed between the magnitude of depolarization (dep) and repolarization (rep) within 3 min: rep (mV) = -(0.24 +/- 0.01) dep (mV) +(2.45 +/- 0.12) mV (r = 0.90). Thus, depolarization is capable to trigger delayed repolarization. The extent of repolarization is a function of the magnitude of depolarization. The possible involvement of calmodulin or arachidonic acid metabolites has been tested for by inducing sodium coupled transport in the presence of 100 mumol/l mepacrine, 10 mumol/l indomethacin or 10 mumol/l trifluoperazine.

UI	MeSH Term	Description	Entries
D007213	Indomethacin	A non-steroidal anti-inflammatory agent (NSAID) that inhibits CYCLOOXYGENASE, which is necessary for the formation of PROSTAGLANDINS and other AUTACOIDS. It also inhibits the motility of POLYMORPHONUCLEAR LEUKOCYTES.	Amuno,Indocid,Indocin,Indomet 140,Indometacin,Indomethacin Hydrochloride,Metindol,Osmosin
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
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
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
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
D011796	Quinacrine	An acridine derivative formerly widely used as an antimalarial but superseded by chloroquine in recent years. It has also been used as an anthelmintic and in the treatment of giardiasis and malignant effusions. It is used in cell biological experiments as an inhibitor of phospholipase A2.	Mepacrine,Acrichine,Atabrine,Atebrin,Quinacrine Dihydrochloride,Quinacrine Dihydrochloride, Dihydrate,Quinacrine Dihyrochloride, (R)-Isomer,Quinacrine Dihyrochloride, (S)-Isomer,Quinacrine Dimesylate,Quinacrine Hydrochloride,Quinacrine Monoacetate,Quinacrine Monohydrochloride,Quinacrine Monomesylate,Quinacrine, (+-)-Isomer,Quinacrine, (R)-Isomer,Quinacrine, (S)-Isomer,Dihydrochloride, Quinacrine,Dimesylate, Quinacrine,Hydrochloride, Quinacrine,Monoacetate, Quinacrine,Monohydrochloride, Quinacrine,Monomesylate, Quinacrine
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
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
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23