[Electrophysiological effects of hyperpolarization activated cyclic nucleotide gated channel 4 overexpression in neonatal cardiomyocytes mediated by recombinant adenovirus].
OBJECTIVE
To explore the electrophysiological effects of hyperpolarization activated cyclic nucleotide gated channel 4 (HCN4) overexpression in rat neonatal cardiomyocytes mediated by recombinant adenovirus.


METHODS
Ventricular cardiomyocytes were obtained from 20 neonatal rats. Recombinant adenovirus carrying HCN4 gene, AdHCN4, a dominant isoform of hyperpolarization activated cyclic nucleotide gated cation channel gene in cardiac transduction system, was constructed and used to transfect the neonatal rat ventricular cardiomyocytes. Untransfected cardiomyocytes were used as controls. RT-PCR and immunofluorescence cytochemistry were used to detect the HCN4 mRNA and protein expression. The electrophysiological characteristics of infected cardiomyocytes were studied by patch clamp.


RESULTS
The mRNA and protein expression levels of HCN4 in AdHCN4 infected cardiomyocytes were both markedly higher than those of the control cardiomyocytes. AdHCN4 caused a significant increase in The spontaneous rate in the transfected cardiomyocytes was 92.5 + 7.4 bpm, significantly higher than that of the control cells (68.9 + 6.2 bpm, P < 0.05). Patch clamp experiments showed that the pacemaker current density in the AdHCN4 infected cardiomyocytes was 115.7 + 7.8 pA/pF, significantly higher than that of the untransfected cells (7.2 + 0.6 pA/pF, P < 0.05).


CONCLUSIONS
Overexpression of HCN4 can enhance the autorhythmicity of neonatal cardiomyocytes and significantly increase the spontaneous beat rate. HCN4 channel gene may represent a candidate gene in gene therapy for bradycardia diseases.
Li
Ji-wen
JW
Department of Cardiology, People's Hospital of Perking University, Beijing 100044, China.
Guo
Ji-hong
JH
Zhang
Ping
P
Li
Chun
C
Liu
Yuan-wei
YW
Zhou
Chun-yan
CY
D000200:Action Potentials; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002460:Cell Line; D054815:Cyclic Nucleotide-Gated Cation Channels; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007473:Ion Channels / Q000096:biosynthesis* / Q000235:genetics; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics; D032383:Myocytes, Cardiac / Q000378:metabolism*; D015221:Potassium Channels; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley
D054815:Cyclic Nucleotide-Gated Cation Channels; C119587:HCN4 protein, human; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007473:Ion Channels; D009124:Muscle Proteins; D015221:Potassium Channels; D012333:RNA, Messenger