Trans- and paracellular K+ transport in diluting segment of frog kidney

1988 ◽  
Vol 411 (3) ◽  
pp. 268-272 ◽  
Author(s):  
Albrecht Schwab ◽  
Hans Oberleithner
Keyword(s):  
Frog Kidney ◽  
Diluting Segment ◽  
K Transport

Amiloride reduces potassium conductance in frog kidney via inhibition of Na+-H+ exchange

1986 ◽  
Vol 251 (1) ◽  
pp. F66-F73
Author(s):  
H. Oberleithner ◽  
G. Munich ◽  
A. Schwab ◽  
P. Dietl
Keyword(s):  
Cell Membrane ◽  
Potassium Conductance ◽  
Membrane Resistance ◽  
Frog Kidney ◽  
High Potassium ◽  
Diluting Segment ◽  
Nephron Segment ◽  
Net Flux ◽  
Kidney Perfusion ◽  
K Concentration

The existence of a carrier-mediated Na+-H+ exchange has been described recently in many epithelial and nonepithelial tissues including the diluting segment of the amphibian kidney. In this preparation the Na+-H+ exchanger is dramatically stimulated by so-called K+ adaptation (chronic exposure of animals to high potassium) and completely inhibited by the diuretic drug amiloride. We performed electrophysiological experiments in diluting segments of the isolated perfused frog kidney to investigate whether amiloride affects the conductance properties of this epithelium. Amiloride dramatically increased the transepithelial resistance and the ratio of lumen over peritubular cell membrane resistance. Cell membrane potential changes, induced by luminal K+ concentration steps, were blunted by luminal application of amiloride, by luminal Na+-free perfusates, or by acidification of the kidney perfusion solution. K+ secretory net flux, measured by K+-sensitive microelectrodes, decreased by half in presence of the diuretic. The experiments reveal that amiloride reduces the K+ conductance of the luminal cell membrane of frog diluting segment via inhibition of the luminal Na+-H+ exchanger. This decreases transepithelial K+ net secretion in this nephron segment.

Contrasting Action of H+ and Ca2+ on K+ Transport in the Diluting Segment of Frog Kidney

1991 ◽  
Vol 1 (5-6) ◽  
pp. 286-293 ◽  
Author(s):  
Christof Schäfer ◽  
Hans-Jürgen Westphale ◽  
Hans Oberleithner
Keyword(s):  
Frog Kidney ◽  
Diluting Segment

Relationship between luminal Na+/H+ exchange and luminal K+ conductance in diluting segment of frog kidney

1985 ◽  
Vol 405 (S1) ◽  
pp. S110-S114 ◽  
Author(s):  
H. Oberleithner ◽  
P. Dietl ◽  
G. M�nich ◽  
M. Weigt ◽  
A. Schwab
Keyword(s):  
Frog Kidney ◽  
Diluting Segment

Mechanism of hydrogen ion transport in the diluting segment of frog kidney

1984 ◽  
Vol 402 (3) ◽  
pp. 272-280 ◽  
Author(s):  
Hans Oberleithner ◽  
Florian Lang ◽  
Georg Messner ◽  
Wenhui Wang
Keyword(s):  
Ion Transport ◽  
Hydrogen Ion ◽  
Frog Kidney ◽  
Diluting Segment ◽  
Hydrogen Ion Transport

Ca2+ transport in diluting segment of frog kidney

1987 ◽  
Vol 410 (1-2) ◽  
pp. 63-68 ◽  
Author(s):  
Paul Dietl ◽  
Hans Oberleithner
Keyword(s):  
Frog Kidney ◽  
Diluting Segment

Aldosterone Stimulates Cellular K+ Uptake and K+ Release in the Diluting Segment of the Frog Kidney

1991 ◽  
Vol 1 (2) ◽  
pp. 89-97 ◽  
Author(s):  
Hans-Jürgen Westphale ◽  
Christof Schäfer ◽  
Hans Oberleithner
Keyword(s):  
Frog Kidney ◽  
Diluting Segment

Electrode sandwich technique: a method for studying K+ transport in renal cells

1988 ◽  
Vol 254 (4) ◽  
pp. F608-F614
Author(s):  
H. J. Westphale ◽  
H. Oberleithner
Keyword(s):  
Steady State ◽  
Renal Tissue ◽  
Dialysis Membrane ◽  
K Uptake ◽  
Frog Kidney ◽  
Sandwich Technique ◽  
Extracellular Compartment ◽  
Net Flux ◽  
Distal Tubules ◽  
K Transport

Distal tubules were harvested from frog kidney and placed on the membrane of a K+-selective macroelectrode. Then the renal tissue was covered with a dialysis membrane to produce a closed extracellular compartment with a constant volume (40 microliter). K+ fluxes in and out of the cells could be determined, since the steady-state K+ activity during constant perfusion changed to a new steady state when perfusion was stopped. Inhibition of passive K+ permeability by the addition of Ba2+ resulted in K+ uptake by the cells because of the function of the Na+-K+ pump. Inhibition of the pump by the addition of ouabain led to K+ efflux from cells reflecting the passive K+ permeability. Because K+ net movement under control conditions (no Ba2+ or ouabain) results from both uptake and efflux, subtraction of K+ uptake (in the presence of Ba2+) from control K+ net flux reveals the passive K+ efflux. This value agrees well with that obtained with ouabain. Furosemide led to a significant K+ shift from the extracellular compartment into the intracellular compartment. Reduction of extracellular pH from 7.8 to 6.0 decreased the rate of K+ uptake by 39 +/- 7% and the K+ leak by 51 +/- 11%. We conclude that K+ uptake and K+ release can be functionally separated. This so-called “electrode sandwich technique” permits evaluation of pump and leak independently in the same cell population.

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