NAF POTENTIATES A K-SELECTIVE ION-CHANNEL IN G292 OSTEOBLASTIC CELLS()

Clinical studies have established that NaF increases mineral content i n bone, although the cellular mechanisms underlying its osteoinductive effects remain unclear. Because metabolic effects of fluoride have be en linked to ion flux and alterations in membrane potential, we used p atch-clamp recording techniques to examine the electrophysiological re sponse of osteoblastic cells to NaF. In these experiments, we show tha t NaF increased the amplitude and P-open of a 73 pS potassium-selectiv e ion channel. The effect of NaF depended on extracellular Ca2+ and co uld be blocked by a combination of calcium-channel blocking agents, su ggesting that potentiation of channel activity was dependent on extern al calcium. Because all patches were in the cell-attached configuratio n, the effect of NaF was presumably indirect. Although the underlying cellular mechanisms remain unclear, our findings suggest that activity of calcium and/or potassium-selective channels via second messenger c ascades may mediate many of the early events involved in the response of bone cells to inorganic fluoride.