Induction of outward current by orexin-B in mouse peritoneal macrophages

To define effects of novel feeding regulating peptides, orexins, in immunoc ompetent cells, ion channel activity in mouse peritoneal macrophages was an alyzed by the perforated patch-clamp method. Orexin-B (OX-B) induced an out ward current at smaller holding potentials than K+ equilibrium potentials, Reversal potentials of OX-B induced current were dependent on external K+ c oncentrations but not on external Cl- concentration. Orexin-A is less effec tive than OX-B, Quinine blocked the outward current and tetraethylammonium partially suppressed the current. These results suggest that OX-B can modul ate macrophage functions through the activation of Ca2+-dependent K2+ chann els. (C) 1998 Federation of European Biochemical Societies.