Chloride transport in the diluting segment of the K+ adapted frog kidney: Effect of amiloride and acidosis

1986 ◽  
Vol 407 (S2) ◽  
pp. S60-S65 ◽  
Author(s):  
Gabi M�nich ◽  
Paul Dietl ◽  
Hans Oberleithner
Keyword(s):  
Chloride Transport ◽  
Frog Kidney ◽  
Diluting Segment

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.

Diluting segment in avian kidney. II. Water and chloride transport

1986 ◽  
Vol 250 (3) ◽  
pp. R341-R347 ◽  
Author(s):  
T. Miwa ◽  
H. Nishimura
Keyword(s):  
Water Permeability ◽  
Chloride Transport ◽  
Arginine Vasotocin ◽  
Osmotic Gradient ◽  
Thick Ascending Limb ◽  
Osmotic Water Permeability ◽  
Diluting Segment ◽  
Henle's Loop ◽  
Osmotic Water ◽  
Avian Kidney

The mammalian-type nephrons of avian kidneys contain a Henle's loop that runs parallel to the collecting ducts and the vasa recta. Thus we examined whether the thick ascending limb (TAL) of Henle's loop of the avian kidney acts as a diluting segment by measuring water and Cl transport in the isolated and perfused TAL of the quail, Coturnix coturnix. The TAL showed a lumen-positive transepithelial voltage (Vt) (+9.4 +/- 0.4 mV, n = 28). Net water flux (Jv) was nearly zero when the TAL was perfused and bathed with isosmotic solution. When the osmotic gradient was imposed, Jv increased only slightly, and thus the osmotic water permeability (Lp) was low. Arginine vasotocin (AVT) added to the hyperosmotic bath did not alter either Jv, Lp, or Vt. Cl efflux (lumen to bath, 370.4 +/- 27.7 peq X mm-1 X min-1) was higher than Cl influx (bath to lumen, 98.6 +/- 14.3 peq X mm-1 X min-1) when measured in the different tubules. AVT showed no effect on Cl efflux. These results indicate that in the TAL of the quail osmotic water permeability is low while net Cl reabsorption is present, suggesting that the TAL functions as a diluting 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
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