Atrial natriuretic peptide (ANP) suppresses acute atrial electrical remodeling in the canine rapid atrial stimulation model.
OBJECTIVE
Atrial electrical remodeling is considered to play an important role in the appearance of atrial fibrillation. The effect of atrial natriuretic peptide (ANP) on atrial electrical remodeling was evaluated in a canine atrial stimulation model.


METHODS
In 15 beagle dogs, electrodes for pacing and recording were fixed on the atrial surface. In 10/15 dogs, rapid atrial stimulation (400 bpm) was performed for 7 h at the right atrial appendage (RAA) and the remaining 5 were used as the sham without rapid pacing. In 5/10 dogs with rapid pacing, human atrial natriuretic peptide (ANP) was infused (1.0 microg/kg/min). The effective refractory period (ERP) and the monophasic action potential duration (MAP) were evaluated at 0, 3, and 7 h after rapid pacing. The expression levels of mRNAs of ion channels or transporters were evaluated from the atrial samples of sham and after a 7 hour pacing.


RESULTS
In the control group with rapid pacing (n=5), the atrial ERP and MAP duration were shortened at all atrial sites, e.g., ERP from 148+/-14 ms to 109+/-8 ms at RAA, P=0.006. In contrast in the ANP group, neither the ERP nor MAP duration showed a significant shortening and the effect of ANP on hemodynamic parameter was relatively small. Expression levels of the mRNA were not significantly different between the control and ANP groups.


CONCLUSIONS
Administration of ANP prevented the shortening of the ERP and MAP duration in the rapid atrial stimulation model. The effect of ANP on atrial electrical remodeling was considered to be due to its direct action on the myocardium.
Yoshida
Toru
T
Department of Emergency and Critical Care Medicine, Kitasato University School of Medicine, 1-15-1, Kitasato, Sagamihara, Kanagawa, 228-8555, Japan. yoshidat@med.kitasato-u.ac.jp
Niwano
Shinichi
S
Niwano
Hiroe
H
Imaki
Ryuta
R
Satoh
Daisuke
D
Masaki
Yoshio
Y
Nakazato
Kazumi
K
Soma
Kazui
K
Izumi
Tohru
T
D000818:Animals; D016275:Atrial Function / Q000187:drug effects* / Q000502:physiology*; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D004285:Dogs; D004594:Electrophysiology
C472955:NPPA protein, human; D009320:Atrial Natriuretic Factor