ISSN:
1432-2013
Keywords:
Amiloride
;
Cl− transport
;
Diluting segment
;
K+ conductance
;
Adaptation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The hypothesis was tested whether amiloride and/or an acute acid load influence Cl− transport in the diluting segment of the isolated-perfused kidney of the K+ adapted frog (rana pipiens). Transepithelial resistance (luminal cable analysis) and Cl− net flux (Cl− sensitive microelectrodes) were evaluated at various concentrations of amiloride, at highpCO2 or low HCO 3 − in the kidney perfusate. Amiloride or an acute acid load increase transepithelial resistance. The resistance-change at given concentrations of amiloride is markedly enhanced under static head conditions, i. e. at low luminal NaCl concentrations. Amiloride or acidosis (highpCO2) reduce Cl− net reabsorption; combination of both potentiates this inhibitory effect. We conclude: an acute acid load acidifies the cell cytosol. This effect is aggravated dramatically after amiloride-induced inhibition of the luminal Na+/H+ exchanger. The luminal pH-sensitive K+ conductance decreases. This results in a depolarization of the cell membranes. Consequently, the peritubular electrochemical driving force for the exit step of Cl− (from cell to blood) dissipates. Therefore, Cl− net reabsorption is blunted.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00584931
Permalink
