Biomaterial Database

Potassium permeability of luminal and peritubular membranes in the proximal tubule of bullfrog kidneys. 1990

M Kubokawa, and T Kubota, and M Fujimoto

Department of Physiology, Osaka Medical College, Takatsuki, Japan.

Using double-barreled K(+)-selective or conventional voltage microelectrode, K+ permeability of the luminal membrane of renal proximal tubule was investigated in comparison with that of the peritubular membrane in doubly-perfused bullfrog kidneys. A decade change in K+ concentration of the luminal perfusate from 3.5 (control) to 35 mM (high K+) induced depolarization in the luminal membrane potential by 11.2 mV with a slight elevation of intracellular K+ activity, (K)i, while those of the peritubular perfusate depolarized peritubular membrane potential by 31.6 mV with a moderate rise of (K)i by 8.0 mEq. The transport number for K+ (tK) in the luminal membrane was about one-third of that in the peritubular membrane. Both luminal and peritubular administrations of Ba2+ (4 mM) additively depolarized membrane potential. The magnitude of Ba2(+)-induced depolarization in the luminal membrane was about one-fourth of that in the peritubular membrane. The high K(+)-induced depolarization elicited from one-side perfusion was hardly affected by Ba2+ which was given from the other side. From these results we conclude that the transport number of K+ in the luminal and peritubular membranes of the proximal tubular epithelium is in the range of 0.17-0.32 and 0.52-0.66, respectively.

UI	MeSH Term	Description	Entries
D007424	Intracellular Fluid	The fluid inside CELLS.	Fluid, Intracellular,Fluids, Intracellular,Intracellular Fluids
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
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
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
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