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Imaging Cleared Embryonic and Postnatal Hearts at Single-cell Resolution
Published on: October 7, 2016
Divergent expression of delayed rectifier K(+) channel subunits during mouse heart development
D Franco1, S Demolombe, S Kupershmidt
1Experimental Molecular Cardiology Group, AMC, University of Amsterdam, Amsterdam, The Netherlands. dfranco@ujaen.es
Cardiovascular Research
|September 15, 2001
Summary
Cardiac action potential repolarization depends on potassium currents. Differential distribution of beta-subunits (KCNE1, KCNE2, KCNE3) in the developing heart, not alpha-subunits (KCNQ1, KCNH2), likely determines atrial versus ventricular current differences.
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Developmental Biology
Background:
- Cardiac action potential repolarization relies on transmembrane K+ currents.
- The delayed-rectifier K+ current comprises slow (I(Ks)) and fast (I(Kr)) components.
- These currents are formed by KCNQ1/KCNH2 alpha-subunits and KCNE1/KCNE2/KCNE3 beta-subunits.
Purpose of the Study:
- To investigate the expression patterns of five potassium channel subunit genes during mouse heart development.
- To examine the protein distribution of KCNQ1 and KCNH2 during cardiac development.
Main Methods:
- Quantitative analysis of mRNA and protein expression.
- In situ hybridization and immunohistochemistry techniques.
- Focus on embryonic day (E) 8.5 to E16.5 mouse heart development.
Main Results:
- KCNQ1 and KCNH2 mRNA and protein are uniformly expressed in atrial and ventricular myocardium from E9.5.
- KCNE1 expression shifts from global to ventricular, while KCNE2 and KCNE3 become restricted to the atrial myocardium during development.
- Alpha-subunits show homogeneous distribution, whereas beta-subunits exhibit regionalized expression.
Conclusions:
- Differential expression of beta-subunits, not alpha-subunits, is the primary determinant of regional differences in cardiac K+ currents.
- This finding provides insight into the molecular basis of electrophysiological heterogeneity between atrial and ventricular cardiomyocytes.
