Influence of potassium depletion on potassium conductance in proximal tubules of frog kidney

1986 ◽  
Vol 407 (2) ◽  
pp. 153-157 ◽  
Author(s):  
G. Messner ◽  
G. Stulnig ◽  
W. Rehwald ◽  
F. Lang
Keyword(s):  
Potassium Conductance ◽  
Proximal Tubules ◽  
Potassium Depletion ◽  
Frog Kidney

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.

Ouabain decreases apparent potassium-conductance in proximal tubules of the amphibian kidney

1985 ◽  
Vol 404 (2) ◽  
pp. 131-137 ◽  
Author(s):  
G. Messner ◽  
W. Wang ◽  
M. Paulmichl ◽  
H. Oberleithner ◽  
F. Lang
Keyword(s):  
Potassium Conductance ◽  
Proximal Tubules ◽  
Amphibian Kidney

Swelling-activated Chloride and Potassium Conductance in Primary Cultures of Mouse Proximal Tubules. Implication of KCNE1 Protein

2003 ◽  
Vol 193 (3) ◽  
pp. 153-170 ◽  
Author(s):  
H. Barri�re ◽  
I. Rubera ◽  
R. Belfodil ◽  
M. Tauc ◽  
N. Tonnerieux ◽  
...  
Keyword(s):  
Primary Cultures ◽  
Potassium Conductance ◽  
Proximal Tubules

Reduction of Potassium in Kidney Proximal Tubules to Aid in Electron Probe X-Ray Microanalysis of Calcium

1985 ◽  
Vol 43 ◽  
pp. 474-475
Author(s):  
A. LeFurgey ◽  
P. Ingram ◽  
L.J. Mandel
Keyword(s):  
Smooth Muscle ◽  
Proximal Tubule ◽  
Electron Probe ◽  
Clinical Applications ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Target Cells ◽  
X Ray ◽  
Freeze Dried

For quantitative determination of subcellular Ca distribution by electron probe x-ray microanalysis, decreasing (and/or eliminating) the K content of the cell maximizes the ability to accurately separate the overlapping K Kß and Ca Kα peaks in the x-ray spectra. For example, rubidium has been effectively substituted for potassium in smooth muscle cells, thus giving an improvement in calcium measurements. Ouabain, a cardiac glycoside widely used in experimental and clinical applications, inhibits Na-K ATPase at the cell membrane and thus alters the cytoplasmic ion (Na,K) content of target cells. In epithelial cells primarily involved in active transport, such as the proximal tubule of the rabbit kidney, ouabain rapidly (t1/2= 2 mins) causes a decrease2 in intracellular K, but does not change intracellular total or free Ca for up to 30 mins. In the present study we have taken advantage of this effect of ouabain to determine the mitochondrial and cytoplasmic Ca content in freeze-dried cryosections of kidney proximal tubule by electron probe x-ray microanalysis.

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