Changes of Notch-1 Expression in Sinoatrial Node Fat Pad of Canines with Chronic Atrial Fibrillation

Abstract

Objective: To investigate the changes of Notch-1 protein expression and the changes of Notch-1 and NICD contents in the sinoatrial node fat pad (SAN-FP) nerve plexus of canines with chronic atrial fibrillation in which atrial fibrillation of the left atrium was induced in chronic pacing canines, in order to elucidate the relationship between the Notch signaling pathway of the SAN-FP nerve plexus and the occurrence and development of atrial fibrillation. Methods: Healthy Beagle dogs weighing 18 ± 2.66 kg, aged 7 to 9 years were randomly divided into a sham operation (SO) group (n = 5) and an atrial fibrillation (AF) group (n = 5), respectively. Results: Atrial fibrillation was successfully induced in canines in the AF group by rapid pacing on the left atrium appendage. The scattered nerve plexus was observed in fat cells of the SAN-FP. In contrast with the SO group, Notch-1 protein expression in the AF group was significantly increased (P < 0.05). No significantly statistical differences were observed in the concentration of Notch-1 and NICD between the AF group and the SO group (P > 0.05). In addition, no statistical differences in baseline Notch-1 and NICD concentrations were observed between the AF group and the SO group (P > 0.05). After an 8-week study, the concentrations of Notch-1 and NICD in the AF group were significantly increased compared with the SO group (P < 0.05). Conclusion: During the occurrence and development of AF, Notch-1 was expressed in different phases in the SAN-FP nerve plexus. After combining with ligands, Notch-1 was activated as NICD to affect the downstream target genes.