[Effects of amiodarone on funny current I(f) channel gene expression in neonatal rat ventricular myocytes].
OBJECTIVE
To analysis the effect of amiodarone on funny current (I(f)) and hyperpolarization-activated cation channel (HCN) gene expressions of the neonatal rat ventricular myocytes.


METHODS
Ventricular myocytes of 1 - 3 days-old rats were isolated and cultured. The cardiomyocytes were treated by amiodarone (0.01, 0.1, 1, 10, 100 micromol/L) for 3 hours or amiodaron (10 micromol/L) for 0, 0.5, 1, 3, 6 hours. The I(f) and HCN 1 - 4 gene expressions were measured through the whole-cell configuration of the patch-clamp technique and real-time quantitative polymerase chain reaction (real-time PCR) using SYBR Green PCR kit.


RESULTS
(1) HCN1, HCN2, HCN3 and HCN4 represented (0.23 +/- 0.01)%, (83.58 +/- 0.04)%, (0.79 +/- 0.01)% and (15.44 +/- 0.01)% of total HCN mRNA, respectively. (2) Amiodaron resulted in a dose-dependent I(f) [(3.1 +/- 0.9)%, (9.7 +/- 2.4)%, (36.7 +/- 5.8)%, (80.3 +/- 1.8)% and (85.9 +/- 3.1)%, respectively at -145 mV, IC(50) (1.32 +/- 0.28) micromol/L], HCN2 [(2.1 +/- 0.8)%, (8.9 +/- 3.6)%, (30.1 +/- 4.2)%, (78.3 +/- 3.6)% and (81.1 +/- 1.9)%, respectively] and HCN4 decrease [(0.5 +/- 0.2)%, (2.1 +/- 2.6)%, (8.8 +/- 3.2)%, (60.1 +/- 4.6)% and (59.6 +/- 6.5)%, respectively]. (3) Amiodaron (10 micromol/L) also induced a time-dependent I(f) [(1.1 +/- 0.1)%, (12.6 +/- 2.3)%, (80.6 +/- 2.2)% and (80.1 +/- 2.1)%, respectively], HCN2 [(1.0 +/- 0.1)%, (9.8 +/- 3.9)%, (82.9 +/- 4.6)% and (83.9 +/- 1.7)%, respectively] and HCN4 decrease [(0.1 +/- 0.1)%, (1.9 +/- 1.1)%, (59.4 +/- 7.8)% and (60.9 +/- 3.1)%, respectively]. However, HCN1 and HCN3 expressions were not affected by amiodaron treatment.


CONCLUSIONS
Current density of I(f) and the expression of HCN2 and HCN4 were decreased by amiodaron which might be the possible antiarrhythmic working mechanisms of amiodaron.
Li
Hong-Xia
HX
Department of the Cardiology, The First Affiliated Hospital of Soochow University, Suzhou, China.
Yang
Xiang-Jun
XJ
Han
Lian-Hua
LH
Zhou
Ya-Feng
YF
Zhao
Xin
X
Jiang
Bin
B
Dong
Ning-Zheng
NZ
Song
Jian-Ping
JP
Liu
Zhi-Hua
ZH
Jiang
Wen-Ping
WP
D000638:Amiodarone / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006352:Heart Ventricles / Q000378:metabolism; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D054815:Cyclic Nucleotide-Gated Cation Channels; C578667:Hcn1 protein, rat; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D015221:Potassium Channels; D000638:Amiodarone