Apr 1, 1991

Blockage of Na+ currents through poorly selective cation channels in the apical membrane of frog skin and toad urinary bladder

Pflügers Archiv : European journal of physiology
W Van DriesscheJ Simaels


The blockage of Na+ movements through the poorly selective cation channels in the apical membrane of frog skin (Rana temporaria) and toad urinary bladder (Bufo marinus) was investigated with noise, impedance analysis and microelectrode techniques. Na+ currents through this pathway were studied with NaCl Ringer solutions on both sides. After removal of Ca2+ and other divalent cations from the mucosal compartment, a considerable part of Isc became insensitive to amiloride. In frog skin, the inhibitory effect of amiloride in mucosal Ca(2+)-free solutions was highly variable. In some experiments a complete lack of inhibition was observed. Similarly, in the absence of amiloride, the inhibitory effect of mucosal Ca2+ varied strongly among frogs. In the absence of mucosal Ca2+, analysis of the fluctuation in Isc revealed a Lorentzian component in the power density spectrum. The corner frequency (fc) of this spontaneous Lorentzian was 12.3 Hz in frog skin and 347 Hz in the toad urinary bladder. In frog skin, nanomolar concentrations of mucosal Ca2+ induced an additional Lorentzian noise component. Its corner frequency shifted upwards with increasing mucosal Ca2+ concentration ([Ca2+]m). The relation between 2 pi fc and [Ca2+]m was line...Continue Reading

  • References22
  • Citations12


  • References22
  • Citations12


Mentioned in this Paper

Establishment and Maintenance of Localization
Biochemical Pathway
Cations, Divalent
Electric Impedance
Neoplasm of Uncertain or Unknown Behavior of Bladder
Bufo marinus

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