Effect of aging-related changes in gap junction protein on arrhythmia in rats / 中华老年医学杂志

ABSTRACT

Objective To investigate the aging-related changes in gap junction protein-connexin 43 (Cx 43) in rats and their effect on the high incidence rate of ventricular arrhythmia in aged rats. Methods The 64 healthy male Fischer 344 (F344) rats were randomly divided into four age groups (n=16,each) 3-6 months (juvenile), 9-12 months (young-adult), 18-21 months (middle-aged) and 24-26 months (aged). The incidence rate of ventricular arrhythmia was recorded by monitoring their limb-lead Electroa rdiogram(ECG). Morphological changes of ventricular myocardium were observed under optical microscope in Hematoxylin (HE) and Masson's stain. The distribution of connexins 43 (Cx43) and deophosphatase (NP) Cx43 was observed by confocal immunofluorescence microscopy and the Cx43 and NP-Cx43 protein expression was assessed by Western-Blot. Results The incidence rate of ventricular arrhythmia was much higher in aged group (75.0%) than in other three groups (0%,0%,12.5%), all P＜0.05, and the aged group showed that ventricular muscle cells were hypertrophy and arrayed sparsely and disorderly with hyperplasia of connective tissues. The distribution of Cx43 changed from end-to-end to disordered arrangement and the total expression amount of Cx43 decreased as age increased (P＜0.05). The expression amount of NP-Cx43 in middle-aged rats was notably decreased than in juvenile and aged rats (P＜0.05). Conclusions For aged rats, the high incidence rate of ventricular arrhythmia may be associated with ventricular myocardium reconstruction, disarrangement of ventricular muscle cells and gap junction proteins, decreased expression amount of Cx43 and relatively increased NP-Cx43.