Modulation of the decay of Ca2+-activated Clâ currents in rabbit portal vein smooth muscle cells by external anions
The effects of external anions on the decay kinetics of Ca 2+ -activated Cl â currents ( I Cl(Ca) ) were studied in smooth muscle cells isolated from rabbit portal vein using the perforated patch whole-cell voltage clamp technique. In normal NaCl-containing external solution the decay of spontaneo...
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Published in | The Journal of physiology Vol. 516; no. 2; p. 365 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
The Physiological Society
15.04.1999
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Online Access | Get full text |
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Summary: | The effects of external anions on the decay kinetics of Ca 2+ -activated Cl â currents ( I Cl(Ca) ) were studied in smooth muscle cells isolated from rabbit portal vein using the perforated patch whole-cell voltage clamp
technique.
In normal NaCl-containing external solution the decay of spontaneous Ca 2+ -activated Cl â currents (STICs) and Ca 2+ -activated Cl â âtailâ currents ( I tail ) was described by a single exponential with a time constant (Ï) that was prolonged by external anions which are more permeable
than Cl â (Br â , I â and SCN â ) and accelerated by less permeant anions. However, intracellular I â did not affect the Ï of STICs and I tail .
There was a positive correlation between the ability of an external anion to affect the decay Ï of I Cl(Ca) and its permeability relative to Cl â .
The voltage dependence of STIC and I tail decay was not affected by external or internal anions.
External permeating anions were not obligatory for activation of I Cl(Ca) and STIC Ï was not altered in Cl â -free external solution.
Modulation of Ï by mole fractions of SCN â and Cl â ions was fitted by a logistic curve, suggesting competition between SCN â and Cl â ions for a binding site.
In conclusion, external anions affect the decay of I Cl(Ca) by a mechanism compatible with an interaction with a binding site which modulates Cl â channel kinetics. |
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ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1111/j.1469-7793.1999.0365v.x |