Relationship of endothelin-1 expression and the changes in collagen fiber distribution in canine chronic atrial fibrillation by rapid left atrial pacing

Abstract

Objective To detect the expression of endothelin-1(ET-1)and the changes in collagen fiber distribution in left and right atrium in a canine model of chronic atrial fibrillation(AF), in order to investigate the relationship of ET-1 and atrial fibrosis in atrial fibrillation. Methods A total of 16 male canines were randomized into 4 groups: Sham group, AF lasting 1 week group(1W group), AF lasting 2 weeks group(2W group)and AF lasting 4 weeks group(4W group)(n=4, each). A canine model of chronic AF was made by rapid left atrial pacing. The mRNA and protein expression levels of ET-1 and collagen type I(COL1)in left and right atrium of canines were measured by real-time quantitative polymerase chain reaction(PCR)and Western Blotting respectively in each group. Collagen fiber deposit in left and right atrium of canines in each group was assessed by Masson's staining. Results Along with prolonged AF duration, the mRNA and protein expression levels of COL1 and ET-1 as well as collagen volume fraction(CVF)in left and right atriums were gradually increased in chronic AF groups of 1-, 2-, 4-weeks duration versus the sham group.CVF: left atrium(5.64±0.63)%, (11.45±1.98)%, (16.71±1.59)% vs. (3.25±0.51)%, right atrium(6.46±0.73)%, (15.01±2.11)%, (20.70±2.37)% vs. (2.72±0.70)%, all P 0.05). Conclusions The distribution of collagen fibers in left and right atriums is anisotropic in a canine model of chronic AF. ET-1 may play an important role in the development of AF by promoting atrial fibrosis. Key words: Atrial fibrillation; Collagen type I; Tachycarclia, ectopic atrial