Chloride channel blockers activate an endogenous cationic current in oocytes of<Emphasis Type="Italic"> Bufo arenarum</Emphasis> |
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Authors: | M?S?Cavarra S?M?del?Mónaco Email author" target="_blank">B?A?KotsiasEmail author |
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Institution: | (1) Facultad de Medicina (UBA), Instituto de Investigaciones Médicas Alfredo Lanari, C. de Malvinas 3150, 1427 Buenos Aires, Argentina;(2) Universidad Maimónides, Buenos Aires, Argentina |
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Abstract: | A two-electrode, voltage-clamp technique was used to measure the effect of the Cl– channel blockers, 9-anthracene carboxylic acid and niflumic acid, upon the ionic currents of oocytes of the South American toad Bufo arenarum. The main results were: (1) both blockers produced a reversible increase of the outward currents on a dose-dependent manner; (2) the activated outward current was voltage dependent; (3) the 9-anthracene carboxylic acid-sensitive current was blocked with barium; and (4) the effect of 9-anthracene carboxylic acid was more pronounced in a zero-K+ solution than in standard (2 mmol l–1) or high (20 mmol l–1) K+ solutions, indicating that a K+ conductance is activated. The effect of the Cl– channel blockers could be due to a direct interaction with endogenous cationic channels. Another possible explanation is that Cl– that enter the cell during depolarizing steps in control solution inhibit this cationic conductance; thus, the blockade of Cl– channels by 9-anthracene carboxylic acid and niflumic acid would remove this inhibition, allowing the cationic current to flow freely.Abbreviations 9-AC 9-anthracene carboxylic acid - Er reversal potential - NA niflumic acid - NSC non-selective cation channel |
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Keywords: | 9-AC Bufo arenarum Ion currents Niflumic acid Oocytes Voltage clamp |
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