Aging and induced atrial fibrillation significantly increased left atrial collagen deposition to 47.86% and 60.24% respectively, compared to 21.96% in adult dogs, and altered If current expression.
Does aging induce atrial fibrosis and alter If current to promote atrial fibrillation in dogs?
Aging promotes atrial fibrillation in dogs by increasing atrial fibrosis and altering ion channel expression, specifically modulating the If current.
Absolute Event Rate: 60.24% vs 21.96%
p-value: p=<0.05
Abstract Background Atrial fibrillation (AF) is a very common type of cardiac arrhythmia that threatens public health. Aging is an independent AF risk factor. However, the mechanism of age‐related AF remains unclear. Methods A total of 36 Beagle dogs were selected and divided into three groups (12 in each group): two groups were 9‐year‐old aged dogs, and one group was 4‐year‐old adult dogs. Electrophysiological testing was employed to determine if modeling is successful. Patch‐clamp technique was employed to measure the I f current. The expression of protein and mRNA related to I f current were also tested. Collagen deposition was observed with the use of Masson staining. Results Aging resulted in a higher collagen deposition percentage in the left atrium. The hyperpolarization‐activated cyclic nucleotide‐gated (HCN)2 and HCN4 expressions were increased in the atria and pulmonary veins but decreased in the sinus node of the aged group. Moreover, in the aged group, the left atrium mRNA expressions of Kcnd2 (Potassium voltage‐gated channel subfamily D member 2), Kcnh2, Kcnq1, Kcnj2, Kcnj11, and CACNA1H were significantly downregulated. The aged AF group also demonstrated sustained AF and significant changes in electrophysiological characteristics. The I f current demonstrated an increased amplitude and was easier to activate in the aged AF group than in younger group. Finally, AF occurrence exacerbated aging‐induced cardiac fibrosis, thereby aggravating the above‐listed symptoms. Conclusion With age, the increase in atrial fibrosis affected the expression of the ion channels, thereby modulating the I f current. Moreover, AF also further exacerbated the degree of atrial fibrosis.
Wang et al. (Mon,) conducted a other in Atrial Fibrillation and Atrial Fibrosis (n=36). Aging and rapid atrial pacing vs. Adult sinus rhythm dogs (4 years old) was evaluated on Left atrial collagen deposition percentage (p=<0.05). Aging and induced atrial fibrillation significantly increased left atrial collagen deposition to 47.86% and 60.24% respectively, compared to 21.96% in adult dogs, and altered If current expression.