One hundred and seventy Wistar rats were enrolled in the study and randomly divided into three groups, i. e. control( C, n = 20, with isotonic saline solution) , burn ( B, n = 90, with isotonic solution after burns) and pyrrolidine dithiocarbamate (PDTC, n =60, with isotonic saline and 250 mg/kg PDTC after burns) groups. The rats in B and PDTC groups were inflicted with 35% TBSA full-thickness burns on the back. The activity of myocardial NF-kappaB was determined by electrophoretic mobility shift assay at 1 , 3, 6, 12,24 postburn hours (PBH), with expression of integral absorbance ( A ) value . The expression of myocardial tumor necrosis factor alpha ( TNF-alpha) mRNA was assessed by reverse transcription polymerase chain reaction( RT-PCR) and in situ hybridization at 6, 12 PBH, with expression ofA value. The left ventricular systolic pressure( LVSP) , the left ventricular end diastolic pressure (LVEDP) ,the maximum rate of rise of left ventricular pressure ( +/- dp/dt max) were also observed at 3, 6, 12,24 PBH. RESULTS The activity of myocardial NF-KB in B group was markedly increased at 1 PBH [ (20. 3+/-3. 4) x 104A ] ,which was obviously higher than that in C group (2. 2 +/- 0. 4) x 104A , P <0.01]. It peaked at 3 PBH, and was still evidently higher than that in C group at 24 PBH ( P <0. 01). The expression of TNF-alpha mRNA was obviously higher than that in C group at 3 PBH ( P < 0. 01) , peaking at 6 PBH, and it was mainly expressed in myocardium. The expression of LVSP and +/- dp/dt max were lower, but LVEDP was higher than that in C group during 3 -24 PBH ( P <0.01).