Role of Cl- channels in α-adrenoceptor-mediated vasoconstriction in the anesthetized rat

Fred S. Lamb, Neil W. Kooy, Stephen J. Lewis

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


In vitro studies have provided evidence that Cl- ion currents are important for activation of vascular smooth muscle contraction. The stilbene, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), disrupts Cl- metabolism by blocking Cl- channels and by inhibiting Cl- bicarbonate exchange. The aims of this study were to: (i) characterize the hemodynamic responses produced by DIDS in pentobarbital anesthetized rats, and (ii) examine vasoconstrictor responses to norepinephrine before and after administration of DIDS. DIDS (2.5-50 μmol/kg, 92.5 μmol/kg total dose, i.v.) produced dose-dependent but transient reductions in mean arterial blood pressure and in hindquarter, renal and mesenteric vascular resistances. Prior to the administration of DIDS, norepinephrine (1.0-5.0 μg/kg, i.v.) produced dose-dependent increases in mean arterial pressure, renal resistance and mesenteric resistance, but decreases in hindquarter resistance that were inversely related to dose. After administration of DIDS, the peak pressor responses produced by norepinephrine were either slightly diminished (1.0, 2.5 μg/kg) or unchanged (5.0 μg/kg). Peak norepinephrine-induced changes in hindquarter and renal vascular resistance were unaffected by DIDS, while increases in mesenteric resistance were augmented. The total norepinephrine-induced increases in mean arterial pressure (mm Hgxs) were markedly reduced by DIDS. These effects of DIDS on norepinephrine-induced responses were similar, but not identical to those of the voltage-sensitive Ca2+ channel blocker, nifedipine (500 nmol/kg, i.v.). These findings suggest that DIDS may interfere with norepinephrine-induced depolarization of resistance arteries, thereby preventing activation of voltage-sensitive Ca2+ channels. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)403-412
Number of pages10
JournalEuropean Journal of Pharmacology
Issue number3
StatePublished - Aug 11 2000

Bibliographical note

Funding Information:
This work was supported in part by National Institute of Health grants HL-62483 and HL-14388 and by grants from the American Heart Association of Iowa.


  • Cl channel
  • Smooth muscle, vascular
  • Stilbene derivative
  • Vasoconstriction


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