Changes in the mRNA levels of delayed rectifier potassium channels in human atrial fibrillation.
BACKGROUND
We measured mRNA levels of delayed rectifier potassium channels in human atrial tissue to investigate the mechanism of the shortening of the atrial effective refractory period and the loss of rate-adaptive shortening of the atrial effective refractory period in human atrial fibrillation.


RESULTS
A total of 34 patients undergoing open heart surgery were included. Atrial tissue was obtained from the right atrial free wall, right atrial appendage, left atrial free wall and left atrial appendage, respectively. The mRNA amounts of KVLQT1 (IKs), minK (beta-subunit of IKs), HERG (IKr), and KV1.5 (IKur) were measured by reverse transcription-polymerase chain reaction and normalized to the mRNA amount of GAPDH. We found that the mRNA levels of KV1.5, HERG and KVLQT1 were all significantly decreased in patients with persistent atrial fibrillation for more than 3 months. In contrast, the mRNA level of minK was significantly increased in patients with persistent atrial fibrillation for more than 3 months. We further showed that these changes were independent of the underlying cardiac disease, atrial filling pressure, gender and age. We also found that there was no spatial dispersion of mRNA levels among the four atrial sampling sites.


CONCLUSIONS
Because the decrease in potassium currents results in a prolonged action potential, the shortening of the atrial effective refractory period in atrial fibrillation should be attributed to other factors. However, the decrease in IKs might contribute, at least in part, to the loss of rate-adaptive shortening of the atrial refractory period.
Lai
L P
LP
Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, ROC.
Su
M J
MJ
Lin
J L
JL
Lin
F Y
FY
Tsai
C H
CH
Chen
Y S
YS
Tseng
Y Z
YZ
Lien
W P
WP
Huang
S K
SK
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D001483:Base Sequence; D001707:Biopsy, Needle; D006348:Cardiac Surgical Procedures; D051668:Delayed Rectifier Potassium Channels; D004594:Electrophysiology; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015221:Potassium Channels / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger / Q000032:analysis*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger