HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 547/1/181    most recent 2002.033688v2 2002.033688v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Piper, A. S. Articles by Large, W. A. Search for Related Content PubMed PubMed Citation Articles by Piper, A. S. Articles by Large, W. A.

Multiple conductance states of single Ca²⁺-activated Cl^- channels in rabbit pulmonary artery smooth muscle cells

A. S. Piper and W. A. Large

Ca²⁺-activated Cl^- channels contribute to agonist-evoked contraction and spontaneous activity in some smooth muscle preparations. Patch pipette techniques were used to study the properties of single Ca²⁺-activated Cl^- channels in freshly dispersed rabbit pulmonary artery myocytes. In the cell-attached recording mode, two conductance states of 3.5 and 1.8 pS were recorded either spontaneously or in response to increasing [Ca²⁺]_i. With inside-out patches, the 3.5 pS channel current predominated at 50 nM [Ca²⁺]_i, but at 500 nM [Ca²⁺]_i most channels opened to the 1.8 pS level and an additional 1.2 pS channel conductance was resolved. At 1 µM [Ca²⁺]_i all of the Cl^- channels opened either to the 1.8 pS or 1.2 pS level. In 0 [Ca²⁺]_i, no channel activity was observed at -100 mV to +100 mV, but with 10-250 nM [Ca²⁺]_i the total single channel open probability (NP_o) increased with depolarisation. This voltage dependence was not seen at higher values of [Ca²⁺]_i. The plot of NP_o vs. [Ca²⁺]_i yielded Ca²⁺ affinity constants of 8 and 250 nM and Hill slopes of 1.3 and 2.3 at +100 and -100 mV, respectively. The distribution of open times was fitted by two exponentials of about 5 and 30 ms, which were neither voltage nor Ca²⁺ dependent. Replacement of external Cl^- by I^- shifted the reversal potential by about -30 mV and lengthened the longer of the two mean open times without significant effects on other kinetic parameters. Based on these data, a model for the activation of Ca²⁺-activated Cl^- channels is proposed.

This article has been cited by other articles:

				R. Bao, L. M. Lifshitz, R. A. Tuft, K. Bellve, K. E. Fogarty, and R. ZhuGe A Close Association of RyRs with Highly Dense Clusters of Ca2+-activated Cl- Channels Underlies the Activation of STICs by Ca2+ Sparks in Mouse Airway Smooth Muscle J. Gen. Physiol., June 30, 2008; 132(1): 145 - 160. [Abstract] [Full Text] [PDF]

				R. Robert, J-P. Savineau, C. Norez, F. Becq, and C. Guibert Expression and function of cystic fibrosis transmembrane conductance regulator in rat intrapulmonary arteries Eur. Respir. J., November 1, 2007; 30(5): 857 - 864. [Abstract] [Full Text] [PDF]

				S. N. Saleh, J. E. Angermann, W. R. Sones, N. Leblanc, and I. A. Greenwood Stimulation of Ca2+-Gated Cl- Currents by the Calcium-Dependent K+ Channel Modulators NS1619 [1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one] and Isopimaric Acid J. Pharmacol. Exp. Ther., June 1, 2007; 321(3): 1075 - 1084. [Abstract] [Full Text] [PDF]

				L.-T. Chien, Z.-R. Zhang, and H. C. Hartzell Single Cl- Channels Activated by Ca2+ in Drosophila S2 Cells Are Mediated By Bestrophins J. Gen. Physiol., August 28, 2006; 128(3): 247 - 259. [Abstract] [Full Text] [PDF]

				O. M. Woodward and A. O. D. Willows Dopamine modulation of Ca2+ dependent Cl- current regulates ciliary beat frequency controlling locomotion in Tritonia diomedea J. Exp. Biol., July 15, 2006; 209(14): 2749 - 2764. [Abstract] [Full Text] [PDF]

				J. E. Angermann, A. R. Sanguinetti, J. L. Kenyon, N. Leblanc, and I. A. Greenwood Mechanism of the Inhibition of Ca2+-Activated Cl- Currents by Phosphorylation in Pulmonary Arterial Smooth Muscle Cells J. Gen. Physiol., June 26, 2006; 128(1): 73 - 87. [Abstract] [Full Text] [PDF]

				L. Johnston, G. P. Sergeant, M. A. Hollywood, K. D. Thornbury, and N. G. McHale Calcium oscillations in interstitial cells of the rabbit urethra J. Physiol., June 1, 2005; 565(2): 449 - 461. [Abstract] [Full Text] [PDF]

				J. Ledoux, I. A. Greenwood, and N. Leblanc Dynamics of Ca2+-Dependent Cl- Channel Modulation by Niflumic Acid in Rabbit Coronary Arterial Myocytes Mol. Pharmacol., January 1, 2005; 67(1): 163 - 173. [Abstract] [Full Text] [PDF]

				A. S. Piper and W. A. Large Direct effect of Ca2+-calmodulin on cGMP-activated Ca2+-dependent Cl-channels in rat mesenteric artery myocytes J. Physiol., September 1, 2004; 559(2): 449 - 457. [Abstract] [Full Text] [PDF]

				A. S. Piper and W. A. Large Single cGMP-activated Ca2+-dependent Cl- channels in rat mesenteric artery smooth muscle cells J. Physiol., March 1, 2004; 555(2): 397 - 408. [Abstract] [Full Text] [PDF]