L-type calcium channels are involved in mediating the anti-inflammatory effects of magnesium sulphate

Magnesium sulphate (MgSO4) has potent anti-inflammatory capacity. It is a natural calcium antagonist and a potent L-type calcium channel inhibitor. We sought to elucidate the possible role of calcium, the L-type calcium channels, or both in mediating the anti-inflammatory effects of MgSO4. RAW264.7 cells, an immortalized murine macrophage-like cell line, were treated with phosphate buffered saline, MgSO4, lipopolysaccharide (LPS), LPS plus MgSO4, LPS plus MgSO4 plus extra-cellular supplement with calcium chloride (CaCl2), or LPS plus MgSO4 plus the L-type calcium channel activator BAY-K8644. After harvesting, the production of inflammatory molecules was evaluated. Because the production of endotoxin-induced inflammatory molecules is regulated by the crucial transcription factor nuclear factor (NF)-kappa B, we also evaluated the expression of NF-kappa B. LPS significantly induced the production of inflammatory molecules, including macrophage inflammatory protein-2, tumour necrosis factor-alpha, interleukin (IL)-1 beta, IL-6, nitric oxide/inducible nitric oxide synthase, and prostaglandin E-2/cyclo-oxygenase-2. LPS also induced NF-kappa B activation, as inhibitor-kappa B degradation, NF-kappa B nuclear translocation, and NF-kappa B-DNA binding activity were significantly increased in LPS-treated RAW264.7 cells. MgSO4, in contrast, significantly inhibited the LPS-induced inflammatory molecules production and NF-kappa B activation. Moreover, the effects of MgSO4 on inflammatory molecules and NF-kappa B were reversed by extra-cellular calcium supplement with CaCl2 and L-type calcium channel activator BAY-K8644. MgSO4 significantly inhibited endotoxin-induced up-regulation of inflammatory molecules and NF-kappa B activation in activated RAW264.7 cells. The effects of MgSO4 on inflammatory molecules and NF-kappa B may involve antagonizing calcium, inhibiting the L-type calcium channels, or both.