| 19617896 |
Wang HD, Lu XX, Lu DX, Qi RB, Wang YP, Fu YM, Wang LW: Glycine inhibits the LPS-induced increase in cytosolic Ca2+ concentration and TNFalpha production in cardiomyocytes by activating a glycine receptor. Acta Pharmacol Sin. 2009 Aug;30(8):1107-14. Epub 2009 Jul 20.
AIM: Previous studies have demonstrated that glycine (GLY) markedly reduces lipopolysaccharide (LPS)-induced myocardial injury.However, the mechanism of this effect is still unclear. The present study investigated the effect of GLY on cytosolic calcium concentration ([Ca2+] c) and tumor necrosis factor-alpha (TNFalpha) production in cardiomyocytes exposed to LPS, as well as whether the glycine-gated chloride channel is involved in this process. METHODS: Neonatal rat cardiomyocytes were isolated, and the [Ca2+] c and TNFalpha levels were determined by using Fura-2 and a Quantikine enzyme-linked immunosorbent assay, respectively. The distribution of the GLY receptor and GLY-induced currents in cardiomyocytes were also investigated using immunocytochemistry and the whole-cell patch-clamp technique, respectively. RESULTS: LPS at concentrations ranging from 10 ng/mL to 100 microg/mL significantly stimulated TNFalpha production. GLY did not inhibit TNFalpha production induced by LPS at concentrations below 10 ng/mL but did significantly decrease TNFalpha release stimulated by 100 microg/mL LPS and prevented an LPS-induced increase in [Ca2+] c, which was reversed by strychnine, a glycine receptor antagonist. GLY did not block the isoproterenol-induced increase in [Ca2+] c, but did prevent the potassium chloride-induced increase in [Ca2+] c in cardiomyocytes.Strychnine reversed the inhibition of the KCl-stimulated elevation in [Ca2+] c by GLY. In chloride-free buffer, GLY had no effect on the dipotassium hydrogen phosphate-induced increase in [Ca2+] c. Furthermore, GLY receptor alpha1 and beta subunit-immunoreactive spots were observed in cardiomyocytes, and GLY-evoked currents were blocked by strychnine. CONCLUSION: Cardiomyocytes possess the glycine-gated chloride channel, through which GLY prevents the increase in [Ca2+] c and inhibits the TNFalpha production induced by LPS at high doses in neonatal rat cardiomyocytes. |
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