Impact of Maternal Vitamin D Receptor (VDR) Gene Polymorphisms on Spontaneous Preterm Birth (Egyptian Case-Control Study)

Abstract

Diverse effects of Ba^(2+) and Co^(2+) on fura-2 fluorescence ratio signals (FR, F350/F380) were examined in cultured bovine aortic endothelial cells (BAECs). ATP (3 μM) induced FR oscillations in normal Ca^(2+)-containing solutions. Co^(2+), but not Ba^(2+), inhibited ATP-induced FR oscillations. In Ca^(2+)-free solutions, 3 μM ATP only elicited a single FR transient. When Ba^(2+) replaced Ca^(2+) in the perfusate, 3 μM ATP provoked a distinct FR transient. The maximal rate of rise of the signal was greater than seen without Ba^(2+) and the FR increased and maintained to a high steady level. When external Ca^(2+) was replaced by Co^(2+), ATP-induced FR transient oscillated with a long recovery time constant. In a survey of the single fluorescence at excitation wavelength 350 nm (F350), Co^(2+) decreased the intensity in the presence of ATP and Ca^(2+). Ba^(2+), however, increased F350 and FR as well, especially in Ca^(2+)-free solutions. The results suggest that ATP-induced Ca^(2+) fluctuation is balanced by Ca^(2+) release from internal stores and influx from external Ca^(2+). Ba2+ seems to be permeable through Ca^(2+) channels and competes with Ca^(2+) for the dye. Co^(2+) blocks Ca^(2+) channels but does not inhibit ATP-mediated Ca^(2+) release in cells.