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Patch Clamp Recording of Ion Channels Expressed in Xenopus Oocytes
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Chloride channel blockers activate an endogenous cationic current in oocytes of Bufo arenarum

M S Cavarra1, S M del Mónaco, B A Kotsias

  • 1Facultad de Medicina (UBA), Instituto de Investigaciones Médicas Alfredo Lanari, C. de Malvinas 3150, 1427 Buenos Aires, Argentina.

Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
|April 23, 2004
PubMed

Insights

Chloride channel blockers 9-anthracene carboxylic acid and niflumic acid increase outward ionic currents in toad oocytes. This suggests these blockers may modulate cationic channels, potentially by removing chloride inhibition.

Area of Science:

  • Physiology
  • Ion Channel Pharmacology
  • Molecular Biology

Background:

  • Chloride (Cl(-)) channels play crucial roles in cellular function.
  • Understanding the regulation of ionic currents is vital in electrophysiology.
  • The specific effects of Cl(-) channel blockers on endogenous currents require elucidation.

Purpose of the Study:

  • To investigate the impact of Cl(-) channel blockers, 9-anthracene carboxylic acid and niflumic acid, on ionic currents in Bufo arenarum oocytes.
  • To explore the mechanisms underlying the observed current changes.
  • To determine the voltage and ion dependency of these effects.

Main Methods:

  • Two-electrode voltage-clamp technique.
  • Application of 9-anthracene carboxylic acid and niflumic acid at varying concentrations.
  • Recording of ionic currents under different ionic conditions (e.g., zero-K(+), varying K(+)).
  • Dose-response and voltage-dependence analysis.

Main Results:

  • Both 9-anthracene carboxylic acid and niflumic acid caused a reversible, dose-dependent increase in outward currents.
  • The activated outward current exhibited voltage dependency.
  • Barium ions blocked the current sensitive to 9-anthracene carboxylic acid.
  • The effect of 9-anthracene carboxylic acid was potentiated in zero-K(+) solution, suggesting K(+) conductance activation.

Conclusions:

  • Cl(-) channel blockers can modulate endogenous cationic conductances in toad oocytes.
  • Blockade of Cl(-) channels may disinhibit cationic currents, leading to increased outward flow.
  • These findings offer insights into the complex interplay between chloride and cationic conductances.

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