Lipopolysaccharide Induced Activation of Toll Like Receptor 4 in Isolated Rat Heart Suggests a Local Immune Response in Myocardium

Background: Myocardial dysfunction is one of the major complications in patients with sepsis where there is a relationship between the blood level of cytokines and the onset of myocardial depression. In many cases of sepsis, the presence of Lipopolysaccharide (LPS) has been established. LPS Binding Protein (LBP) bound endotoxin is recognized by CD14/toll-like receptor-4 (TLR4) complexes in innate immune cells which stimulates TNF-α release. Objectives: To investigate whether isolated rat heart is capable of producing TNF-α locally through TLR4 activation by LPS. Methods: Using langendorff method, LPS in 120 mL of the modified KrebsHenseleit buffer solution (KHBS) at final concentration of 1 µg/mL was perfused at recycling mode. The effect of LPS on cardiac function was evaluated. To assess the TLR4 activity and TNF-α release, western blotting, real time-PCR, and ELISA were used. Results: Compared with control, coronary perfusion pressure (CPP) as well as left ventricular developed pressure (LVDP), maximum and minimum rates of the left ventricular developed pressure (dP/dtmax; dP/dtmin; p