ISSN:
1432-2013
Keywords:
Cl Channel
;
Vascular smooth muscle cells
;
DIDS
;
SITS
;
Zn
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effects of Cl channel blockers on large-conductance (LC-type) Cl channels of cultured vascular smooth muscle cells (VSMC) were studied in order to characterize the channel pharmacologically. Intracellular disulphonic stilbene derivatives, such as 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid (DIDS) and 4-acetamido-4-isothiocyanostilbene-2,2′-disulphonic acid (SITS) inhibited Cl channel activity in a dose-dependent manner. An obvious inhibitory effect of DIDS in this condition was obtained at concentrations higher than 5 μM, and the complete inhibition was obtained at around 100 μM, which was almost 10 times less than the effective dose of SITS. The inhibitory effect of DIDS was reversible at a drug concentration of lower than 50 μM. Single-channel conductance decreased as the concentration of DIDS increased. This decrease in the conductance was a consequence of unresolved openings of the channel due to fast blocking and unblocking rates of the drug. The Cl channel was also obviously inhibited by extracellular DIDS at a concentration of 1 mM. In addition, in cell-attached patches, 500 μM DIDS applied extracellularly inhibited Cl channel activated by the application of polymyxin B. We also investigated the effect of Zn on Cl channels in VSMC. Intracellular Zn dose dependently and reversibly blocked the channel at the positive intracellular potential range, whereas at the negative intracellular potential range it did not block the channel activity. Results in this study suggest the diversity of Cl channels among various tissues.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00370515
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