Biomaterial Database

The effect of diffusible ions on the peritubular membrane potential of proximal tubular cells in perfused bullfrog kidneys. 1980

T Kubota, and M Honda, and K Kotera, and M Fujimoto

Effects of extracellular diffusible ions, such as K+, Cl- and HCO3- (pH), on the peritubular membrane potential (EM) and intracellular activities of K+, (K)i, or Cl-, (Cl)i, were studied in the perfused proximal tubule of bullfrog kidneys with K+ or Cl- -selective microelectrodes. In steady-state conditions, in which both the peritubular and luminal sides were perfused with control Ringer solutions, the K+ equilibrium potential (EK) always exceeded the EM by approximately 19 mV and correlated well with the EM (correlation coefficient r = 0.78), whereas no correlation was recognized between the equilibrium potential of Cl-(ECl) and the EM. In the quick peritubular perfusion experiments, in which the extracellular diffusible ions were changed, the (K)i and (Cl)i were maintained relatively stable. The following facts were observed: (1) At constant EK, decreasing the peritubular chloride (Cl)e produced a small degree of hyperpolarization of the EM instead of depolarization. (2) At constant ECl, increasing the (K)e depolarized the EM. (3) At constant PCO2, the EM was depolarized with low HCO3- (acid) perfusions, while it was hyperpolarized with high HCO3- (alkaline) perfusions. These results are in agreement with the views that, 1) intracellular K+ in the proximal tubule is maintained by an uphill uptake mechanism on the peritubular cell membrane, (2) the ionic conductance of peritubular membrane is relatively high to K+, but low to Cl-, and (3) the pH gradient across the peritubular membrane can modulate the passive permeability to Na+ or K+.

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
D008297	Male		Males
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
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.
D011892	Rana catesbeiana	A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.	Bullfrog,Bullfrogs,Rana catesbeianas,catesbeiana, Rana
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
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
D001639	Bicarbonates	Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the pH of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity.	Bicarbonate,Bicarbonate Ions,Hydrogen Carbonates,Bicarbonate Ion,Carbonic Acid Ions,Hydrogen Carbonate,Carbonate, Hydrogen,Carbonates, Hydrogen,Ion, Bicarbonate,Ions, Bicarbonate,Ions, Carbonic Acid