Adrenocorticotropic hormone activates an outward current in cultured mouseperitoneal macrophages

To define the effects of adrenocorticotropic hormone (ACTH) in immunocompet ent cells, ion channel activities in cultured mouse peritoneal macrophages were analyzed by the perforated patch-clamp method. ACTH induced outward cu rrents at smaller holding potentials than K+ equilibrium potentials. Revers al potentials of ACTH-induced currents were dependent on external K+ concen trations, but not on external Cl- concentration. Quinine potently blocked t he outward current and tetraethylammonium (TEA) partially suppressed that c urrent. ACTH did not induce the response in Ca2+-free solution containing E GTA. These results suggest that ACTH can modulate macrophage functions thro ugh the activation of Ca2+-dependent K+ channels. (C) 2001 Elsevier Science BN. All rights reserved.