K(ir)2.1 encodes the inward rectifier potassium channel in rat arterial smooth muscle cells

Karri K. Bradley, Jonathan Jaggar, Adrian D. Bonev, Thomas J. Heppner, Elaine R.M. Flynn, Mark T. Nelson, Burton Horowitz

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Abstract

1. The molecular nature of the strong inward rectifier K+ channel in vascular smooth muscle was explored by using isolated cell RT-PCR, cDNA cloning and expression techniques. 2. RT-PCR of RNA from single smooth muscle cells of rat cerebral (basilar), coronary and mesenteric arteries revealed transcripts for K(ir)2.1. Transcripts for K(ir)2.2 and K(ir)2.3 were not found. 3. Quantitative PCR analysis revealed significant differences in transcript levels of K(ir)2.1 between the different vascular preparations (n = 3; P < 0.05). A two-fold difference was detected between K(ir)2.1 mRNA and β-actin mRNA in coronary arteries when compared with relative levels measured in mesenteric and basilar preparations. 4. K(ir)2.1 was cloned from rat mesenteric vascular smooth muscle cells and expressed in Xenopus oocytes. Currents were strongly inwardly rectifying and selective for K+. 5. The effect of extracellular Ba2+, Ca2+, Mg2+ and Cs2+ ions on cloned K(ir)2.1 channels expressed in Xenopus oocytes was examined. Ba2+ and Cs+ block were steeply voltage dependent, whereas block by external Ca2+ and Mg2+ exhibited little voltage dependence. The apparent half-block constants and voltage dependences for Ba2+, Cs+, Ca2+ and Mg2+ were very similar for inward rectifier K+ currents from native cells and cloned K(ir)2.1 channels expressed in oocytes. 6. Molecular studies demonstrate that K(ir)2.1 is the only member of the K(ir)2 channel subfamily present in vascular arterial smooth muscle cells. Expression of cloned K(ir)2.1 in Xenopus oocytes resulted in inward rectifier K+ currents that strongly resemble those that are observed in native vascular arterial smooth muscle cells. We conclude that K(ir)2.1 encodes for inward rectifier K+ channels in arterial smooth muscle.

Original languageEnglish (US)
Pages (from-to)639-651
Number of pages13
JournalJournal of Physiology
Volume515
Issue number3
DOIs
StatePublished - Mar 15 1999

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Inwardly Rectifying Potassium Channel
Vascular Smooth Muscle
Smooth Muscle Myocytes
Oocytes
Xenopus
Polymerase Chain Reaction
Coronary Vessels
Messenger RNA
Basilar Artery
Mesenteric Arteries
Cerebral Arteries
Smooth Muscle
Blood Vessels
Actins
Organism Cloning
Complementary DNA
RNA
Ions

All Science Journal Classification (ASJC) codes

  • Physiology

Cite this

Bradley, K. K., Jaggar, J., Bonev, A. D., Heppner, T. J., Flynn, E. R. M., Nelson, M. T., & Horowitz, B. (1999). K(ir)2.1 encodes the inward rectifier potassium channel in rat arterial smooth muscle cells. Journal of Physiology, 515(3), 639-651. https://doi.org/10.1111/j.1469-7793.1999.639ab.x

K(ir)2.1 encodes the inward rectifier potassium channel in rat arterial smooth muscle cells. / Bradley, Karri K.; Jaggar, Jonathan; Bonev, Adrian D.; Heppner, Thomas J.; Flynn, Elaine R.M.; Nelson, Mark T.; Horowitz, Burton.

In: Journal of Physiology, Vol. 515, No. 3, 15.03.1999, p. 639-651.

Research output: Contribution to journalArticle

Bradley, KK, Jaggar, J, Bonev, AD, Heppner, TJ, Flynn, ERM, Nelson, MT & Horowitz, B 1999, 'K(ir)2.1 encodes the inward rectifier potassium channel in rat arterial smooth muscle cells', Journal of Physiology, vol. 515, no. 3, pp. 639-651. https://doi.org/10.1111/j.1469-7793.1999.639ab.x
Bradley, Karri K. ; Jaggar, Jonathan ; Bonev, Adrian D. ; Heppner, Thomas J. ; Flynn, Elaine R.M. ; Nelson, Mark T. ; Horowitz, Burton. / K(ir)2.1 encodes the inward rectifier potassium channel in rat arterial smooth muscle cells. In: Journal of Physiology. 1999 ; Vol. 515, No. 3. pp. 639-651.
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