What are arrhythmogenic substrates in diabetic rat atria?
BACKGROUND
Diabetes mellitus is one of the significant independent risk factors for the development of atrial fibrillation (AF). However, the pathophysiological mechanisms of the relationship have not been fully elucidated.


RESULTS
The genetic type II diabetes (GK) rats and their original (Wistar) ones were subjected to electrophysiological (n = 8 per group) and histological (n = 7 per group) studies. At 40 weeks old, when GK rats had significantly (P < 0.01) more increased plasma glucose and HbA(1c) values than Wistar rats, atrial electrical stimuli in the isolated-perfused hearts induced significantly greater number of repetitive atrial responses in GK rats than in Wistar rats (47.9 +/- 17.5 vs 3.1 +/- 1.3 beats, respectively, P < 0.01). GK rats showed significantly longer intra-atrial activation time than Wistar rats (18.3 +/- 0.4 ms vs 15.9 +/- 0.5 ms, P < 0.01) without any significant difference in the atrial refractoriness. The histological examination revealed significantly increased diffuse fibrotic deposition in GK rats atria compared with Wistar ones (P < 0.01).


CONCLUSIONS
The present diabetic GK rat showed increased atrial arrhythmogenicity with intra-atrial conduction disturbance, and thus indicated that the structural remodeling of atrium characterized by diffuse interstitial fibrosis would be a major substrate for diabetes-related AF.
Kato
Takeshi
T
Cardiovascular Institute, Tokyo, Japan. takeshikato@mac.com
Yamashita
Takeshi
T
Sekiguchi
Akiko
A
Sagara
Kouichi
K
Takamura
Masayuki
M
Takata
Shigeo
S
Kaneko
Shuichi
S
Aizawa
Tadanori
T
Fu
Long-Tai
LT
D000818:Animals; D001281:Atrial Fibrillation / Q000209:etiology* / Q000503:physiopathology; D001786:Blood Glucose / Q000032:analysis; D048909:Diabetes Complications / Q000209:etiology*; D005355:Fibrosis; D006442:Glycated Hemoglobin / Q000032:analysis; D006325:Heart Atria / Q000473:pathology; D008297:Male; D009206:Myocardium / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D006442:Glycated Hemoglobin