BACKGROUND:

In the advanced stages of chronic heart failure (CHF) the expression of inducible nitric oxide synthase (iNOS) in skeletal muscle (SM) may contribute to exercise intolerance and early fatigue. Cell culture studies and promoter analysis demonstrated that the transcription factor nuclear factor kappa B (NF-kappaB) is essential for iNOS-expression. The aim of this study was to assess whether NF-kappaB is activated in skeletal muscle of patients with CHF and linked to the expression of iNOS.

METHODS:

Skeletal muscle biopsies were obtained from seven CHF patients and seven healthy controls (HC). Nuclear proteins were isolated and the content of activated NF-kappaB was analysed by electrophoretic mobility shift assay (EMSA). Inducible nitric oxide synthase expression in SM was determined by real time polymerase chain reaction (PCR).

RESULTS:

The expression of iNOS (1.4 +/- 0.2 versus 0.5 +/- 0.08 arbitrary units, P=0.001) and the activation of NF-kappaB in the SM (0.5 +/- 0.1 versus 0.1 +/- 0.04 arbitrary units, P=0.009) was significantly increased in CHF patients as compared to healthy controls. Furthermore, a linear correlation was observed between NF-kappaB activation and iNOS expression (r=0.78, P<0.001).

CONCLUSIONS:

The results of this study indicate for the first time that in the skeletal muscle of patients with chronic heart failure the activation of the transcription factor NF-kappaB is increased and may represent one important regulatory factor for the expression of iNOS in patients. Nevertheless, due to the small sample size this observation has to be confirmed in subsequent studies with more patients.