Published online before print April 10, 2003, doi: 10.1161/01.RES.0000070880.20955.F4
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on October 24, 2002
Revised on March 4, 2003
Accepted on March 24, 2003
Molecular Variants of KCNQ Channels Expressed in Murine Portal Vein Myocytes. A Role in Delayed Rectifier Current
Susumu Ohya ;
From the Department of Physiology and Cell Biology (S.O., G.P.S., B.H.), University of Nevada School of Medicine, Reno, Nev; the Department of Molecular and Cellular Pharmacology (S.O.), Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan; and the Department of Pharmacology and Clinical Pharmacology (I.A.G.), St George's Hospital Medical School, London, UK.
* To whom correspondence should be addressed. E-mail: burt{at}physio.unr.edu.
We have analyzed the expression of KCNQ genes in murine portal vein myocytes and determined that of the 5 known KCNQ channels, only KCNQ1 was expressed. In addition to the full-length KCNQ1 transcript, a novel spliced form (termed KCNQ1b) was detected that had a 63 amino acid truncation at the C-terminus. KCNQ1b was not detected in heart or brain but represented approximately half the KCNQ1 transcripts expressed in PV. Antibodies specific for KCNQ1a stained cell membranes from portal vein myocytes and HEK cells expressing the channel. However, because the antibodies were generated against an epitope in the deleted, C-terminal portion of the protein, these antibodies did not stain HEK cells expressing KCNQ1b. In murine portal vein myocytes, in the presence of 5 mmol/L 4-aminopyridine, an outwardly rectifying K+ current was recorded that was sensitive to linopirdine, a specific blocker of KCNQ channels. Currents produced by the heterologous expression of KCNQ1a or KCNQ1b were inhibited by similar concentrations of linopirdine, and linopirdine prolonged the time-course of the action potential in isolated portal vein myocytes. Our data suggest that these two KCNQ1 splice forms are expressed in murine portal vein and contribute to the delayed rectifier current in these myocytes.
Key words: smooth muscle • voltage-dependent potassium channels • linopirdine
This article has been cited by other articles:
 |
|
 |
|
  T. A. Jepps, I. A. Greenwood, J. D. Moffatt, K. M. Sanders, and S. Ohya Molecular and functional characterization of Kv7 K+ channel in murine gastrointestinal smooth muscles Am J Physiol Gastrointest Liver Physiol, July 1, 2009; 297(1): G107 - G115. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Joshi, V. Sedivy, D. Hodyc, J. Herget, and A. M. Gurney KCNQ Modulators Reveal a Key Role for KCNQ Potassium Channels in Regulating the Tone of Rat Pulmonary Artery Smooth Muscle J. Pharmacol. Exp. Ther., April 1, 2009; 329(1): 368 - 376. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. D. Luykenaar, R. A. El-Rahman, M. P. Walsh, and D. G. Welsh Rho-kinase-mediated suppression of KDR current in cerebral arteries requires an intact actin cytoskeleton Am J Physiol Heart Circ Physiol, April 1, 2009; 296(4): H917 - H926. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Lange, J. Geissendorfer, A. Schenzer, J. Grotzinger, G. Seebohm, T. Friedrich, and M. Schwake Refinement of the Binding Site and Mode of Action of the Anticonvulsant Retigabine on KCNQ K+ Channels Mol. Pharmacol., February 1, 2009; 75(2): 272 - 280. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. R. Mackie and K. L. Byron Cardiovascular KCNQ (Kv7) Potassium Channels: Physiological Regulators and New Targets for Therapeutic Intervention Mol. Pharmacol., November 1, 2008; 74(5): 1171 - 1179. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. R. Mackie, L. I. Brueggemann, K. K. Henderson, A. J. Shiels, L. L. Cribbs, K. E. Scrogin, and K. L. Byron Vascular KCNQ Potassium Channels as Novel Targets for the Control of Mesenteric Artery Constriction by Vasopressin, Based on Studies in Single Cells, Pressurized Arteries, and in Vivo Measurements of Mesenteric Vascular Resistance J. Pharmacol. Exp. Ther., May 1, 2008; 325(2): 475 - 483. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. L. Shang, A. E. Pfahnl, S. Sanyal, Z. Jiao, J. Allen, K. Banach, J. Fahrenbach, D. Weiss, W. R. Taylor, A. M. Zafari, et al. Human Heart Failure Is Associated With Abnormal C-Terminal Splicing Variants in the Cardiac Sodium Channel Circ. Res., November 26, 2007; 101(11): 1146 - 1154. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. D. Luykenaar and D. G. Welsh Activators of the PKA and PKG pathways attenuate RhoA-mediated suppression of the KDR current in cerebral arteries Am J Physiol Heart Circ Physiol, June 1, 2007; 292(6): H2654 - H2663. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Y. Yeung, P. Sathiagnanam, J. Moffatt, V. Pucovsky, and I. Greenwood KCNQ gene expression in the murine vasculature FASEB J, April 1, 2007; 21(6): A1411 - A1411.
|
|
|
|
|
|
L. I. Brueggemann, C. J. Moran, J. A. Barakat, J. Z. Yeh, L. L. Cribbs, and K. L. Byron Vasopressin stimulates action potential firing by protein kinase C-dependent inhibition of KCNQ5 in A7r5 rat aortic smooth muscle cells Am J Physiol Heart Circ Physiol, March 1, 2007; 292(3): H1352 - H1363. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Connolly, D. Whittaker, I. Greenwood, P. Aaronson, and R. Tribe Evidence for a role of KCNQ channels in regulating contractility in rat myometrium FASEB J, March 1, 2006; 20(5): A1241 - A1241.
|
|
|
|
 |
|
 S. J. Fountain, A. Cheong, R. Flemming, L. Mair, A. Sivaprasadarao, and D. J. Beech Functional up-regulation of KCNA gene family expression in murine mesenteric resistance artery smooth muscle J. Physiol., April 1, 2004; 556(1): 29 - 42. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. D. Luykenaar, S. E. Brett, B. N. Wu, W. B. Wiehler, and D. G. Welsh Pyrimidine nucleotides suppress KDR currents and depolarize rat cerebral arteries by activating Rho kinase Am J Physiol Heart Circ Physiol, March 1, 2004; 286(3): H1088 - H1100. [Abstract] [Full Text] [PDF]
|
|