Figure 6.

Mg²⁺ regulates endothelial barrier integrity through S1P1‐Rac1. A) TER measurements with the treatment of Mg²⁺ (2 mmol L⁻¹) or Mg²⁺‐deficiency (0.1 mmol L⁻¹). Cells were transfected with siRNA against TRPM7, MagT1 or scramble control siRNA, and cultured to confluency in transwell. B) Trans‐endothelial permeability to dextran (40 kD) measurements with the treatment of Mg²⁺ (2 mmol L⁻¹) or Mg²⁺‐deficiency (0.1 mmol L⁻¹). C) siRNA knockdown of S1P1. Western blots showing protein expression of S1P1 in endothelial cells after treated with control siRNA or siRNA against S1P1; and quantitative measurements of relative S1P1 protein levels from Western blots (right). D) TER measurements with the treatment of Mg²⁺ (2 mmol L⁻¹) in cells with downregulation of Rac1 or S1P1 using siRNA or S1P1 specific inhibitor W146. E) Trans‐endothelial permeability to dextran (40 kD) with the treatment of Mg²⁺ (2 mmol L⁻¹) in cells with downregulation of Rac1 or S1P1 using siRNA or S1P1 specific inhibitor W146. F) Rac1‐GRP activity with or without Mg²⁺ treatment. G) Phosphorylation of S1P1 with or without Mg²⁺ treatment. *P < 0.05, vs Mg²⁺‐deficiency or group treated with MagT1 siRNA and TRPM7 siRNA. (*P < 0.05, vs Mg²⁺‐deficiency or group treated with MagT1 siRNA and TRPM7 siRNA; **P < 0.01, vs Mg²⁺‐deficiency or group treated with MagT1 siRNA and TRPM7 siRNA; n = 4).