The direct effect of lipopolysaccharide on an isolated heart is different from the effect on cardiac myocytes in vitro

Figures

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  Figure 1. Direct effects of LPS on cardiac contractility in isolated rat hearts using a Langendorff apparatus. Changes in left ventricular function after treatment with LPS at different concentrations in a Langendorff-perfused heart. A – Quantification of contractile function. B – Beat rate *P < 0.05 and **p < 0.01 vs. the vehicle-treated control group. #P < 0.05 vs. the 5 μg/kg LPS-treated group, n = 6.

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  Figure 2. Direct effects of LPS on the TLR4 signalling pathway in H9c2 cells. A – Representative pictures of Western blots, with each signal indicated. Quantified protein levels were calculated for TLR4 (B), JAK2 (C), and STAT3 (D). E – Changes in the cardiac contractile protein myosin light chain (MLC)-2 were compared. F – LPS (5 μg/ml) increased cellular calcium accumulation, which was suppressed by inhibitors including GIT-27, AG490, and Stattic at the indicated concentrations *P < 0.05 and **p < 0.01 vs. the vehicle-treated control (first column). #P < 0.05 vs. another LPS-treated group (second column), n = 4.

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  Figure 3. Apoptosis induced by LPS in H9c2 cells. Western blot detection of apoptotic biomarkers that were promoted by LPS treatment at the indicated concentrations after a short (3 h) incubation (A) or longer (24 h) treatment (C). The upper panel shows the representative responses, and quantification of the levels is indicated in the last column. Additionally, apoptosis in H9c2 cells was characterised by flow cytometry after a short (3 h) incubation (B) or longer (24 h) treatment (D) with LPS at the indicated dose. The side-scatter intensity (vertical axis) is plotted against the fluorescence intensity in the APC channel (horizontal axis) *P < 0.05 and **p < 0.01 vs. the vehicle-treated control (first column). #P < 0.05 and ##P < 0.01 vs. the low-dose LPS-treated group (second column), n = 4.

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  Figure 4. The role of proinflammatory cytokines in the toxic effects of LPS on H9c2 cells. Cells were treated with LPS (1 μg/ml or 5 μg/ml) or vehicle for 3, 12, and 24 h; cells were treated with or without BAY11-7082 (10 μmol/l) 30 mins before LPS (5 μg/ml) treatment. A – IL-6 mRNA expression, B – TNF-α mRNA expression, C – lactate dehydrogenase (LDH) release, D – CaSR mRNA expression *P < 0.05 was compared between the 5 μg/ml LPS-treated group and the LPS (5 μg/ml), BAY11-7082-treated group, n = 6.

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  Figure 5. Effects of specific inhibitors on the changes induced by LPS. NPS2390 at the dose required to block the calcium-sensing receptor (CaSR) may reverse the apoptosis induced by LPS at a high dose after a short incubation (A) or at a low dose after longer treatment (C). CaSR mRNA levels were increased by LPS treatment after either a short incubation time at a high dose (B) or a longer incubation time at a low dose (D) *P < 0.05 and **p < 0.01 vs. the vehicle-treated control (first column). #P < 0.05 and ##P < 0.01 vs. the low dose LPS-treated group (second column).