Properties of a Cl- current activated by cell swelling in rabbit portal vein vascular smooth muscle cells.
In rabbit portal vein smooth muscle cells, application of a hypotonic external solution caused cell swelling and evoked an outwardly rectifying Cl- current. The hypotonicity-activated current was markedly reduced by the anti-estrogen tamoxifen (10 microM) and was inhibited by DIDS in a voltage-dependent manner [the concentration required to inhibit the current by 50% (IC50) at -50 and +100 mV was 21 and 5 microM DIDS, respectively]. Indanyloxyacetic acid 94 (IAA-94) and niflumic acid also inhibited the hypotonicity-activated current, with 50% inhibition produced at concentrations of approximately 200 and 100 microM, respectively. In isotonic conditions, application of tamoxifen and DIDS to cells decreased the holding current due to the inhibition of a resting conductance that was outwardly rectifying and reversed at the Cl- equilibrium potential. These data show that rabbit portal vein myocytes have a resting Cl- conductance that is enhanced by cell swelling; its possible physiological role is discussed.
Greenwood
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Department of Pharmacology and Clinical Pharmacology, St. George's Cardiovascular Research Group, St. George's Hospital Medical School, London SW17 0RE, United Kingdom.
Large
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D000818:Animals; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions; D009131:Muscle, Smooth, Vascular / Q000473:pathology / Q000502:physiology*; D011169:Portal Vein / Q000473:pathology / Q000502:physiology*; D011817:Rabbits; D013629:Tamoxifen / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D007038:Hypotonic Solutions; D013629:Tamoxifen; D004958:Estradiol