[Time course of myocardial NF-kappaB activation post coronary microembolization]

Abstract

Objective: To investigate the time course of myocardial NF-kappaB activation and association with cardiac function and other pro-inflammation cytokines following coronary microembolization (CME).

Methods: CME was induced by homologous microthrombotic particle suspension injection into left ventricle with simultaneous short-term ascending aorta clamping. The CME rats were randomized to untreated group and pyrrolidine dithiocarbamate (PDTC, a specific NF-kappaB inhibitor) treated group (n = 32 respectively). The rats were sacrificed on day 1, 3, 7 and 14 post-operationally (n = 8 each). Twenty-four rats were sham-operated and served as controls. NF-kappaB DNA-binding activity was evaluated by electrophoretic mobility shift assay (EMSA), protein expressions of TNFalpha, IL-6 and ICAM-1 were analyzed by Western blotting, the dynamic alterations of TNFalpha, IL-6 and ICAM-1 mRNA were quantitatively assessed by Real-time PCR post hemodynamic measurements.

Results: NF-kappaB DNA-binding activity in CME group was significantly increased than that of sham group on day 1, peaked at day 3 and was similar as that in sham rats on day 14. The protein and mRNA expressions of TNFalpha, IL-6 and ICAM-1 were significantly increased in CME group at various time points compared those in sham rats. NF-kappaB DNA-binding activity positively correlated with mRNA expressions of TNFalpha, IL-6, ICAM-1, respectively (r = 0.72, P < 0.05; r = 0.94, P < 0.01; r = 0.62, P < 0.05). PDTC significantly suppressed protein and mRNA expressions of TNFalpha, IL-6 and ICAM-1 (P < 0.05) and improved left ventricular function.

Conclusion: NF-kappaB activation post CME could upregulate the gene transcriptions of TNFalpha, IL-6, ICAM-1 and enhance inflammatory responses and aggravate left ventricular dysfunction.