ACTIVATION OF LARGE-CONDUCTANCE CA2-ACTIVATED K+ CHANNELS IN N1E-115 NEUROBLASTOMA-CELLS BY PLATELET-ACTIVATING-FACTOR()

Using patch-clamp single channel recording techniques, we reported a P latelet-Activating Factor ''PAF''-induced activation of large conducta nce Ca2+-activated K+ ''BK(Ca)'' channels in N1E-115 cells. This activ ation was only observed in cell-attached configuration and was blocked by the PAF antagonist BN50739 or removal of calcium from the bath. Na nomolar concentration of PAF produced a transient hyperpolarization ob served in whole-cell current clamp configuration which was blocked by the bath application of BN50739 or iberiotoxin. Our results suggest th at the PAF-induced hyperpolarization is mediated by an activation of B K(Ca) channels coupled to specific PAF receptors. This coupling is not direct and results from the PAF-induced elevation in cytosolic free C a2+ concentrations that we have previously described in N1E-115 cells (Cell Calcium 1995, 17, 442-452). (C) 1996 Academic Press, Inc.