Functional Expression of Inward Rectifier Potassium Channels in Cultured Human Pulmonary Smooth Muscle Cells: Evidence for a Major Role of Kir2.4 Subunits

Functional Expression of Inward Rectifier Potassium Channels in Cultured Human Pulmonary Smooth... Strong inwardly rectifying K+ (KIR) channels that contribute to maintaining the resting membrane potential are encoded by the Kir2.0 family (Kir2.1–2.4). In smooth muscle, KIR currents reported so far have the characteristics of Kir2.1. However, Kir2.4, which exhibits unique characteristics of barium block, has been largely overlooked. Using patch-clamp techniques, we characterized KIR channels in cultured human pulmonary artery smooth muscle (HPASM) cells and compared them to cloned Kir2.1 and Kir2.4 channels. In a physiological K+ gradient, inwardly rectifying currents were observed in HPASM cells, the magnitude and reversal potential of which were sensitive to extracellular K+ concentration. Ba2+ (100 μM) significantly inhibited inward currents and depolarized HPASM cells by ∼10 mV. In 60 mM extracellular K+, Ba2+ blocked KIR currents in HPASM cells with a 50% inhibitory concentration of 39.1 μM at –100 mV compared to 3.9 μM and 65.6 μM for Kir2.1 and Kir2.4, respectively. Cloned Kir2.4 and KIR currents in HPASM cells showed little voltage dependence to Ba2+ inhibition, which blocked at a more superficial site than for Kir2.1. Single-channel recordings revealed strong inwardly rectifying channels with an average conductance of 21 pS in HPASM cells, not significantly different from either Kir2.1 (19.6 pS) or Kir2.4 (19.4 pS). Reverse-transcription polymerase chain reaction detected products corresponding to Kir2.1, Kir2.2 and Kir2.4 but not Kir2.3. We demonstrate that cultured HPASM cells express KIR channels and suggest both Kir2.1 and Kir2.4 subunits contribute to these channels, although the whole-cell current characteristics described share more similarity with Kir2.4. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Functional Expression of Inward Rectifier Potassium Channels in Cultured Human Pulmonary Smooth Muscle Cells: Evidence for a Major Role of Kir2.4 Subunits

Loading next page...
 
/lp/springer_journal/functional-expression-of-inward-rectifier-potassium-channels-in-2nOz7AcViC
Publisher
Springer-Verlag
Copyright
Copyright © 2007 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-006-0037-y
Publisher site
See Article on Publisher Site

Abstract

Strong inwardly rectifying K+ (KIR) channels that contribute to maintaining the resting membrane potential are encoded by the Kir2.0 family (Kir2.1–2.4). In smooth muscle, KIR currents reported so far have the characteristics of Kir2.1. However, Kir2.4, which exhibits unique characteristics of barium block, has been largely overlooked. Using patch-clamp techniques, we characterized KIR channels in cultured human pulmonary artery smooth muscle (HPASM) cells and compared them to cloned Kir2.1 and Kir2.4 channels. In a physiological K+ gradient, inwardly rectifying currents were observed in HPASM cells, the magnitude and reversal potential of which were sensitive to extracellular K+ concentration. Ba2+ (100 μM) significantly inhibited inward currents and depolarized HPASM cells by ∼10 mV. In 60 mM extracellular K+, Ba2+ blocked KIR currents in HPASM cells with a 50% inhibitory concentration of 39.1 μM at –100 mV compared to 3.9 μM and 65.6 μM for Kir2.1 and Kir2.4, respectively. Cloned Kir2.4 and KIR currents in HPASM cells showed little voltage dependence to Ba2+ inhibition, which blocked at a more superficial site than for Kir2.1. Single-channel recordings revealed strong inwardly rectifying channels with an average conductance of 21 pS in HPASM cells, not significantly different from either Kir2.1 (19.6 pS) or Kir2.4 (19.4 pS). Reverse-transcription polymerase chain reaction detected products corresponding to Kir2.1, Kir2.2 and Kir2.4 but not Kir2.3. We demonstrate that cultured HPASM cells express KIR channels and suggest both Kir2.1 and Kir2.4 subunits contribute to these channels, although the whole-cell current characteristics described share more similarity with Kir2.4.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Mar 8, 2007

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off