Molecular and functional characterization of Kv4.2 and KChIP2 expressed in the porcine left ventricle.
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Molecular and functional characterization of Kv4.2 and KChIP2 expressed in the porcine left ventricle. / Schultz, Jobst-Hendrik; Volk, Tilmann; Bassalaý, Peter; Hennings, J Christopher; Hübner, Christian; Ehmke, Heimo.
In: PFLUG ARCH EUR J PHY, Vol. 454, No. 2, 2, 2007, p. 195-207.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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T1 - Molecular and functional characterization of Kv4.2 and KChIP2 expressed in the porcine left ventricle.
AU - Schultz, Jobst-Hendrik
AU - Volk, Tilmann
AU - Bassalaý, Peter
AU - Hennings, J Christopher
AU - Hübner, Christian
AU - Ehmke, Heimo
PY - 2007
Y1 - 2007
N2 - Recent studies showed that the Ca(2+)-independent transient outward current (I (to)) is very small or even not detectable in the porcine left ventricle. We investigated whether an altered molecular expression or function of voltage-dependent potassium channels belonging to the Kv4 sub-family and their ancillary Ca(2+)-binding beta sub-unit KChIP2, which contribute to the major fraction of I (to )in other species, may underlie this lack of a significant I (to) in the porcine left ventricle. RT-PCR analysis with degenerate primers showed that both Kv4 mRNA and KChIP2 mRNA are expressed in porcine left ventricular tissue and in isolated ventricular myocytes. PCR cloning and sequence analysis predicted proteins with >98% identity to rat and human Kv4.2 and >99% identity to rat and human KChIP2. Heterologous expression of porcine Kv4.2 in Xenopus laevis oocytes gave rise to currents with characteristic properties of rat and human Kv4.2, and co-expression with its KChIP2 sub-unit increased current density (tenfold), slowed inactivation (twofold) and accelerated recovery from inactivation (tenfold). Kv4.2 immunohistochemistry in porcine left ventricular tissue revealed a predominant membrane-bound signal. Relative quantification of gene expression indicated that Kv4.2 and KChIP2 mRNA and protein are expressed at comparable ratios in porcine and rat left ventricular tissues, which displays a large I (to). Collectively, these data demonstrate that the lack of a significant I (to) in the porcine left ventricle does not result from dysfunctional or insufficiently expressed Kv4.2 and KChIP2 sub-units.
AB - Recent studies showed that the Ca(2+)-independent transient outward current (I (to)) is very small or even not detectable in the porcine left ventricle. We investigated whether an altered molecular expression or function of voltage-dependent potassium channels belonging to the Kv4 sub-family and their ancillary Ca(2+)-binding beta sub-unit KChIP2, which contribute to the major fraction of I (to )in other species, may underlie this lack of a significant I (to) in the porcine left ventricle. RT-PCR analysis with degenerate primers showed that both Kv4 mRNA and KChIP2 mRNA are expressed in porcine left ventricular tissue and in isolated ventricular myocytes. PCR cloning and sequence analysis predicted proteins with >98% identity to rat and human Kv4.2 and >99% identity to rat and human KChIP2. Heterologous expression of porcine Kv4.2 in Xenopus laevis oocytes gave rise to currents with characteristic properties of rat and human Kv4.2, and co-expression with its KChIP2 sub-unit increased current density (tenfold), slowed inactivation (twofold) and accelerated recovery from inactivation (tenfold). Kv4.2 immunohistochemistry in porcine left ventricular tissue revealed a predominant membrane-bound signal. Relative quantification of gene expression indicated that Kv4.2 and KChIP2 mRNA and protein are expressed at comparable ratios in porcine and rat left ventricular tissues, which displays a large I (to). Collectively, these data demonstrate that the lack of a significant I (to) in the porcine left ventricle does not result from dysfunctional or insufficiently expressed Kv4.2 and KChIP2 sub-units.
M3 - SCORING: Zeitschriftenaufsatz
VL - 454
SP - 195
EP - 207
JO - PFLUG ARCH EUR J PHY
JF - PFLUG ARCH EUR J PHY
SN - 0031-6768
IS - 2
M1 - 2
ER -