Effect of magnesium on secretion of platelet-derived growth factor by cultured human umbilical arterial endothelial cells.

Conditioned media were prepared by incubating human cultured umbilical arterial endothelial cells for 48 h in magnesium (Mg) sufficient (900 microM) and deficient (100 microM) conditions. Minimum essential media (MEM) are designated as [900]- and [100]-MEM, respectively. After the incubation, a portion of the [100]-MEM media was adjusted from 100 to 900 microM magnesium ([100-900]-MEM). Smooth muscle cells were incubated with the three media and their growth rates were determined by [3H]-thymidine incorporation and cell counting. The growth rate in [100-900]-MEM was significantly higher than in [900]- or [100]-MEM. When platelet-derived growth factor (PDGF) was neutralized by the addition of a mixture of anti-PDGF-AA and -BB, [3H]-thymidine incorporation in [100-900]-MEM decreased by 12.5 per cent, but only by 4.9 per cent in [900]-MEM. These results indicate that magnesium deficiency increases the secretion of PDGF by endothelial cells. This is also supported by the results of the radioimmunoassay for PDGF-BB; the quantity of PDGF in the magnesium-deficient media was greater than in the magnesium-sufficient media.