Dynamics of Ca2+-Dependent Cl- Channel Modulation by Niflumic Acid in Rabbit Coronary Arterial Myocytes
Open Access
- 1 October 2004
- journal article
- Published by American Society for Pharmacology & Experimental Therapeutics (ASPET)
- Vol. 67 (1), 163-173
- https://doi.org/10.1124/mol.104.004168
Abstract
Calcium-activated chloride channels (ClCa) are crucial regulators of vascular tone by promoting a depolarizing influence on the resting membrane potential of vascular smooth muscle cells. Niflumic acid (NFA), a potent blocker of ClCa in vascular myocytes, was shown recently to cause inhibition and paradoxical stimulation of sustained calcium-activated chloride currents [ICl(Ca)] in rabbit pulmonary artery myocytes. The aims of the present study were to investigate whether NFA produced a similar dual effect in coronary artery smooth muscle cells and to determine the concentration-dependence and dynamics of such a phenomenon. Sustained ICl(Ca) evoked by intracellular Ca2+ clamped at 500 nM were dose-dependently inhibited by NFA (IC50 = 159 μM) and transiently augmented in a concentration-independent manner (10 μM to 1 mM) ∼2-fold after NFA removal. However, the time to peak and duration of NFA-enhanced ICl(Ca) increased in a concentration-dependent fashion. Moreover, the rate of recovery was reduced by membrane depolarization, suggesting the involvement of a voltage-dependent step in the interaction of NFA, leading to stimulation of ICl(Ca). Computer simulations derived from a kinetic model involving low (Ki = 1.25 mM) and high (Ki < 30 μM) affinity sites could reproduce the properties of the NFA-modulated ICl(Ca) fairly well.Keywords
This publication has 21 references indexed in Scilit:
- The Cl− channel blocker niflumic acid releases Ca2+ from an intracellular store in rat pulmonary artery smooth muscle cellsBritish Journal of Pharmacology, 2003
- Comparison of the properties of CLCA1 generated currents and ICl(Ca) in murine portal vein smooth muscle cellsThe Journal of Physiology, 2002
- Differential regulation of Ca2+‐activated Cl− currents in rabbit arterial and portal vein smooth muscle cells by Ca2+‐calmodulin‐dependent kinaseThe Journal of Physiology, 2001
- Ca2+-dependent activation of Cl−currents in Xenopus oocytes is modulated by voltageAmerican Journal of Physiology-Cell Physiology, 2000
- Inhibitory action of niflumic acid on noradrenaline- and 5-hydroxytryptamine-induced pressor responses in the isolated mesenteric vascular bed of the ratBritish Journal of Pharmacology, 1997
- Activation of calcium-dependent chloride channels in rat parotid acinar cells.The Journal of general physiology, 1996
- Effect of niflumic acid on noradrenaline-induced contractions of the rat aortaBritish Journal of Pharmacology, 1996
- Comparison of the effects of fenamates on Ca‐activated chloride and potassium currents in rabbit portal vein smooth muscle cellsBritish Journal of Pharmacology, 1995
- Action of niflumic acid on evoked and spontaneous calcium‐activated chloride and potassium currents in smooth muscle cells from rabbit portal veinBritish Journal of Pharmacology, 1994
- Effects of Cl channel blockers on Ca‐activated chloride and potassium currents in smooth muscle cells from rabbit portal veinBritish Journal of Pharmacology, 1994