In vivo cardiac gene transfer of Kv4.3 abrogates the hypertrophic response in rats after aortic stenosis.
BACKGROUND
Prolongation of the action potential duration (APD) and decreased transient outward K+ current (I(to)) have been consistently observed in cardiac hypertrophy. The relation between electrical remodeling and cardiac hypertrophy in vivo is unknown.


RESULTS
We studied rat hearts subjected to pressure overload by surgical ascending aortic stenosis (AS) and simultaneously infected these hearts with an adenovirus carrying either the Kv4.3 gene (Ad.Kv4.3) or the beta-galactosidase gene (Ad.beta-gal). I(to) density was reduced and APD50 was prolonged (P<0.05) in AS rats compared with sham rats. Kv4.2 and Kv4.3 expressions were decreased by 58% and 51%, respectively (P<0.05). AS rats infected with Ad.beta-gal developed cardiac hypertrophy compared with sham rats, as assessed by cellular capacitance and heart weight-body weight ratio. Associated with the development of cardiac hypertrophy, the expression of calcineurin and its downstream transcription factor nuclear factor of activated T cells (NFAT) c1 was persistently increased by 47% and 36%, respectively (P<0.05) in AS myocytes infected with Ad.beta-gal compared with sham myocytes. In vivo gene transfer of Kv4.3 in AS rats was shown to increase Kv4.3 expression, increase I(to) density, and shorten APD50 by 1.6-fold, 5.3-fold, and 3.6-fold, respectively (P<0.05). Furthermore, AS rats infected with Ad.Kv4.3 showed significant reductions in calcineurin and NFAT expression. (P<0.05).


CONCLUSIONS
Downregulation of I(to), APD prolongation, and cardiac hypertrophy occur early after AS, and in vivo gene transfer of Kv4.3 can restore these electrical parameters and abrogate the hypertrophic response via the calcineurin pathway.
Lebeche
Djamel
D
Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Mass 02129, USA.
Kaprielian
Roger
R
del Monte
Federica
F
Tomaselli
Gordon
G
Gwathmey
Judith K
JK
Schwartz
Arnold
A
Hajjar
Roger J
RJ
D000200:Action Potentials / Q000235:genetics / Q000502:physiology; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001024:Aortic Valve Stenosis / Q000150:complications*; D019703:Calcineurin / Q000096:biosynthesis / Q000235:genetics; D020013:Calcium Signaling; D006332:Cardiomegaly / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D002478:Cells, Cultured / Q000502:physiology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D003673:Defective Viruses / Q000235:genetics; D005786:Gene Expression Regulation; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000627:therapeutic use*; D017136:Ion Transport; D008297:Male; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000502:physiology; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000502:physiology; D051672:Shal Potassium Channels; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014161:Transduction, Genetic; D014463:Ultrasonography
D004268:DNA-Binding Proteins; C497023:Kcnd3 protein, rat; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D024642:Potassium Channels, Voltage-Gated; D011993:Recombinant Fusion Proteins; D051672:Shal Potassium Channels; D014157:Transcription Factors; D019703:Calcineurin; D011188:Potassium