Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Comparison of cloned Kir2 channels with native inward rectifier K + channels from guinea‐pig cardiomyocytes

Comparison of cloned Kir2 channels with native inward rectifier K + channels from guinea‐pig... 1 The aim of the study was to compare the properties of cloned Kir2 channels with the properties of native rectifier channels in guinea‐pig (gp) cardiac muscle. The cDNAs of gpKir2.1, gpKir2.2, gpKir2.3 and gpKir2.4 were obtained by screening a cDNA library from guinea‐pig cardiac ventricle. 2 A partial genomic structure of all gpKir2 genes was deduced by comparison of the cDNAs with the nucleotide sequences derived from a guinea‐pig genomic library. 3 The cell‐specific expression of Kir2 channel subunits was studied in isolated cardiomyocytes using a multi‐cell RT‐PCR approach. It was found that gpKir2.1, gpKir2.2 and gpKir2.3, but not gpKir2.4, are expressed in cardiomyocytes. 4 Immunocytochemical analysis with polyclonal antibodies showed that expression of Kir2.4 is restricted to neuronal cells in the heart. 5 After transfection in human embryonic kidney cells (HEK293) the mean single‐channel conductance with symmetrical K+ was found to be 30.6 pS for gpKir2.1, 40.0 pS for gpKir2.2 and 14.2 pS for Kir2.3. 6 Cell‐attached measurements in isolated guinea‐pig cardiomyocytes (n= 351) revealed three populations of inwardly rectifying K+ channels with mean conductances of 34.0, 23.8 and 10.7 pS. 7 Expression of the gpKir2 subunits in Xenopus oocytes showed inwardly rectifying currents. The Ba2+ concentrations required for half‐maximum block at ‐100 mV were 3.24 μm for gpKir2.1, 0.51 μm for gpKir2.2, 10.26 μm for gpKir2.3 and 235 μm for gpKir2.4. 8 Ba2+ block of inward rectifier channels of cardiomyocytes was studied in cell‐attached recordings. The concentration and voltage dependence of Ba2+ block of the large‐conductance inward rectifier channels was virtually identical to that of gpKir2.2 expressed in Xenopus oocytes. 9 Our results suggest that the large‐conductance inward rectifier channels found in guinea‐pig cardiomyocytes (34.0 pS) correspond to gpKir2.2. The intermediate‐conductance (23.8 pS) and low‐conductance (10.7 pS) channels described here may correspond to gpKir2.1 and gpKir2.3, respectively. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Physiology Wiley

Comparison of cloned Kir2 channels with native inward rectifier K + channels from guinea‐pig cardiomyocytes

Download PDF
12 pages

Loading next page...
 
/lp/wiley/comparison-of-cloned-kir2-channels-with-native-inward-rectifier-k-gZT5uLLcKo

References (51)

Publisher
Wiley
Copyright
Copyright © 2001 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0022-3751
eISSN
1469-7793
DOI
10.1111/j.1469-7793.2001.0115g.x
Publisher site
See Article on Publisher Site

Abstract

1 The aim of the study was to compare the properties of cloned Kir2 channels with the properties of native rectifier channels in guinea‐pig (gp) cardiac muscle. The cDNAs of gpKir2.1, gpKir2.2, gpKir2.3 and gpKir2.4 were obtained by screening a cDNA library from guinea‐pig cardiac ventricle. 2 A partial genomic structure of all gpKir2 genes was deduced by comparison of the cDNAs with the nucleotide sequences derived from a guinea‐pig genomic library. 3 The cell‐specific expression of Kir2 channel subunits was studied in isolated cardiomyocytes using a multi‐cell RT‐PCR approach. It was found that gpKir2.1, gpKir2.2 and gpKir2.3, but not gpKir2.4, are expressed in cardiomyocytes. 4 Immunocytochemical analysis with polyclonal antibodies showed that expression of Kir2.4 is restricted to neuronal cells in the heart. 5 After transfection in human embryonic kidney cells (HEK293) the mean single‐channel conductance with symmetrical K+ was found to be 30.6 pS for gpKir2.1, 40.0 pS for gpKir2.2 and 14.2 pS for Kir2.3. 6 Cell‐attached measurements in isolated guinea‐pig cardiomyocytes (n= 351) revealed three populations of inwardly rectifying K+ channels with mean conductances of 34.0, 23.8 and 10.7 pS. 7 Expression of the gpKir2 subunits in Xenopus oocytes showed inwardly rectifying currents. The Ba2+ concentrations required for half‐maximum block at ‐100 mV were 3.24 μm for gpKir2.1, 0.51 μm for gpKir2.2, 10.26 μm for gpKir2.3 and 235 μm for gpKir2.4. 8 Ba2+ block of inward rectifier channels of cardiomyocytes was studied in cell‐attached recordings. The concentration and voltage dependence of Ba2+ block of the large‐conductance inward rectifier channels was virtually identical to that of gpKir2.2 expressed in Xenopus oocytes. 9 Our results suggest that the large‐conductance inward rectifier channels found in guinea‐pig cardiomyocytes (34.0 pS) correspond to gpKir2.2. The intermediate‐conductance (23.8 pS) and low‐conductance (10.7 pS) channels described here may correspond to gpKir2.1 and gpKir2.3, respectively.

Journal

The Journal of Physiology – Wiley

Published: Apr 1, 2001

There are no references for this article.