LPS induces cardiac depression via toll-like receptor 4 on cardiac myocytes

摘要

Toll-like receptor 4, TLR4, binds lipopolysaccharide, LPS. TLR4 is expressed on immune cells but also on cardiac myocytes. Sepsis is accompanied by cardiac depression and decreasing blood pressure finally leading to septic shock. Therefore we monitored the effects of LPS on sarcomere shortening of isolated cardiac myocytes with and without intact TLR.4 signaling.Cardiac myocytes of C3H/HeN (control) and C3H/HeJ (TLR4-D) mice were isolated and sarcomere shortening (0.5 - 10 Hz) was recorded optically. LPS (1 or 10 pg/ml) influence was allowed to develop during short term culture (1-8 h) of the cells. To prevent LPS dependent influences an iNOS blocker S-methylisothiourea (SMT; 100 pg/ml) or a TLR4 antagonist (E5564, Eisai, 2 pg/ml) were added to the culture medium. After i.p. injection of 20 mg/kg LPS cardiac tissue was investigated for phosphorylation of MAP-kinases by western blot, NF-kB activation by electromobility shift assays and iNOS expression by RT-PCR.