Inward rectification in mouse macrophages: evidence for a negative resistance region.
The electrical properties of cultured mouse thioglycollate-induced peritoneal macrophages were investigated using intracellular recording techniques. Thirty-five percent of the cells studied had membrane potentials ranging from -65 to -95 mV and exhibited S-shaped, steady-state current-voltage (I-V) relationships containing a transitional region. Analysis of currents in the transitional region from the rate of rise and fall of the voltage responses to current pulses indicated the presence of a negative resistance region in this area. Tetrodotoxin (3 X 10(-5) M), cobalt chloride (3 mM), 4-aminopyridine (4 mM), and tetraethylammonium chloride (8 mM) did not eliminate the transitional region of the I-V curves, whereas addition of barium chloride (4 mM) and rubidium chloride (3 mM) did. Increasing the external concentration of potassium shifted the I-V relationship horizontally along the current axis but did not eliminate the transitional region. These data indicate that the inward rectification and the negative resistance region probably result from a voltage-dependent potassium conductance.
D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D008264:Macrophages / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D012413:Rubidium / Q000494:pharmacology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D000631:Aminopyridines; D009467:Neuromuscular Depolarizing Agents; D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D012413:Rubidium