Atorvastatin, etanercept and the nephrogenic cardiac sympathetic remodeling in chronic renal failure rats

Abstract

Background: Chronic renal failure (CRF) patients are predisposed to arrhythmias, while the detailed mechanisms are unclear. We hypothesized the chronic inflammatory state of CRF patients may lead to cardiac sympathetic remodeling, increasing the incidence of ventricular arrhythmia (VA) and sudden cardiac death. And explored the role of atorvastatin and etanercept in this process.

Methods: A total of 48 rats were randomly divided into sham operation group (Sham group), CRF group, CRF + atorvastatin group (CRF + statin group), and CRF + etanercept group (CRF + rhTNFR-Fc group). Sympathetic nerve remodeling was assessed by immunofluorescence of growth-associated protein 43 (GAP-43) and tyrosine hydroxylase positive area fraction. Electrophysiological testing was performed to assess the incidence of VA by assessing the ventricular effective refractory period and ventricular fibrillation threshold. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta were determined by Western blotting and enzyme-linked immunosorbent assay.

Results: Echocardiogram showed that compared with the Sham group, left ventricular end-systolic diameter and ventricular weight/body weight ratio were significantly higher in the CRF group. Hematoxylin-eosin and Masson staining indicated that myocardial fibers were broken, disordered, and fibrotic in the CRF group. Western blotting, enzyme-linked immunosorbent assay, immunofluorescence and electrophysiological examination suggested that compared with the Sham group, GAP-43 and TNF-α proteins were significantly upregulated, GAP-43 and tyrosine hydroxylase positive nerve fiber area was increased, and ventricular fibrillation threshold was significantly decreased in the CRF group. The above effects were inhibited in the CRF + statin group and the CRF + rhTNFR-Fc group.

Conclusions: In CRF rats, TNF-α was upregulated, cardiac sympathetic remodeling was more severe, and the nephrogenic cardiac sympathetic remodeling existed. Atorvastatin and etanercept could downregulate the expression of TNF-α or inhibit its activity, thus inhibited the above effects, and reduced the occurrence of VA and sudden cardiac death.

Figure 1

Comparisons of body weight (A) and serum creatinine values (B) in the four groups.

Figure 2

Comparisons of transthoracic echocardiogram indexes (A) and blood pressure indexes (B) in the four groups.

Figure 3

Hematoxylin-eosin (× 200) (A) and Masson staining (× 400) (B) results in left ventricular tissue of the four groups.

Figure 4

Comparison of the electrophysiological indicators in the four groups.

Figure 5

Comparison of protein expression levels of GAP-43 and NGF in the four groups.

Figure 6

The immunofluorescence results of GAP-43 positive nerves in left ventricular tissue of the four groups (× 400).

Figure 7

The immunofluorescence results of TH positive nerves in left ventricular tissue in the four groups (× 400).

Figure 8

Comparison of GAP-43 and TH positive nerve density in the four groups.

Figure 9

Comparison of the concentrations of TNF-α and IL-1β in left ventricular tissue (A) and comparison of protein expression levels of TNF-α in the four groups (B).