1α,25(OH)2Vitamin D3-Mediated Stimulation of Outward Anionic Currents in Osteoblast-like ROS 17/2.8 Cells

1 alpha,25-dihydroxyvitamin-D3 [1 alpha,25(OH)2D3] is known to potentiate in osteoblast-like rat osteosarcoma cells (ROS 17/2.8) the influx of Ca2+ through voltage-activated L-type Ca2+ channels. In the present study, by means of the whole-cell patch-clamp technique, we found that physiological concentrations of 1 alpha,25(OH)2D3 (5-5000 x 10(-11) M) also stimulate, in a dose-dependent manner, outwardly rectifying anionic currents over the course of 1-5 minutes. These currents, recorded in the presence of 130 mM glutamate or approximately 140 mM C1- in the external solution, were blocked by 200 microM DIDS, a stilbene derivative selective for C1- channels. We conclude that, in addition to the already known effects of 1 alpha,25(OH)2D3 on Ca2+ channels, the hormone also enhances in ROS 17/2.8 cells an outward anion conductance. This is the first report concerning activation of anion channels by 1 alpha,25(OH)2D3.