| Cardiac dysfunction occurs during septic shock as one of the common complications. It is reported that about 40% patients with septic shock suffer from left and right ventricular function. It is generally accepted that most of sepsis are caused by Gram-negative bacterial infection. Endotoxin, a lipopolysaccharide (LPS) component of the outer membrane of Gram-negative bacteria, plays important roles in this infectious process. Although! the mechanism of LPS-induced myocardial dysfunction is incompletely described, it has recently been established that upregulation of tumor necrosis factora (TNFa) levels and abnormal calcium cycling in cardiomyocytes are responsible for the mechanisms of LPS-induced myocardial dysfunction. On the other hand, there is a lot of the available information regarding the effects of berberine (Ber) on cardiac dysfunction, such as positive inotropic action, negative frequency, treatment of congestive heart failure. However, it is still unclear whether berberine has a prophylaxis and therapeutic effect on LPS-induced myocardial dysfunction. Therefore, our experiments were conducted to determine whether berberine would reduce LPS-induced cardiac dysfunction and test whether berberine would affect the intracellular free calcium concentration ([Ca2+]j) and TNFa production in LPS-treated cardiomtocytes, which provides a new therapeutic measurement and experimental evidence for the treatment of LPS-induced cardiac dysfunction .Methods:This experiment was carried out in three parts: Firstly, the Langendoff perfusion of isolated rat hearts was used to to explore the effect of berberine on LPS-induced cardiac dysfunction. Secondly, neonatal rat cardiomyocytes (SD rats of 1-3 d) were cultured, and fluorescent indicator fura-2 was used to measure intracellular free calcium concentration ([Ca2+] i) for examining the effects of KC1, isoproterenol (ISO), LPS and/or Ber on [Ca2+] j in cardiomyocytes. Lastly, neonatal rat cardiomyocytes (SD rats of 1-3 d) were cultured. TNFa levels in supernatant were determined by an enzyme-linked immunosorbent assay (ELISA) to3LPSinvestigate the effect of Ber on the TNFa secretion from cardiomyocytes treated with LPS.Results:1. 10-min Ber (10~6 mol/L) perfusion, 20-min LPS(100 \igJmL) perfusion and 10-min Ber (10 6 mol/L) following 20-min LPS (100 |xg/mL) perfusion all induced a significant decrease in heart rate at 120 min after perfusion compared to baseline at 0 min (P<0.05), which was not found in control hearts. Perfusion of isolated heart with LPS (100 jig/mL) for 20 min resulted in significantly impaired cardiac performance (Langendorff preparation) at 120 min after LPS challenge, maximal rate of left ventricular pressure rise and fall( + d/?/dî–³ax) decreased compared with control; On the contrary , + d/VdJmax of the heart perfused withlO-min Ber (10~6 mol/L following 20-min LPS (100 ^ig/mL) at 120 min was higher than that in LPS group.2. Intracellular free calcium concentration ([Ca +]\) in cardiomyocytes was significantly increased after stimulation with 50 mmol/L KC1 in control, whereas there was no detectable difference in [Ca2+] ; after stimulation with KC1 in berberine pretreatment group. ISO stimulated a increase in [Ca2+] \ in cardiomyocytes in both control and berberine pretreatment group. Furthermore, [Ca2+] ; was significantly increased after LPS stimulation for 10 min in control, and pretreatment with different concentrations of berberine (1, 2 V- mol/L) didn't inhibit LPS-induced [Ca2+] ; elevation in cardiomyocytes. [Ca2+] \ was significantly decreased after 1 h LPS treatment compared to control group, whereas [Ca2+] \ was significantly increased after 1 h berberine treatment compare to control group. [Ca2+] \ in berberine plus LPS group was higher than that in LPS group but with no detectable difference compared to control.3. LPS at different doses (1, 5, 10, 20 U g/mL) stimulated TNFa secretion from cardiomyocytes, and Ber (2, 4 nmol/mL) inhibited LPS-induced TNFa production.Conclusion:... |
