A patch-clamp study of histamine-secreting cells.
The ionic conductances in rat basophilic leukemia cells (RBL-2H3) and rat peritoneal mast cells were investigated using the patch-clamp technique. These two cell types were found to have different electrophysiological properties in the resting state. The only significant conductance of RBL-2H3 cells was a K+-selective inward rectifier. The single channel conductance at room temperature increased from 2-3 pS at 2.8 mM external K+ to 26 pS at 130 mM K+. This conductance, which appeared to determine the resting potential, could be blocked by Na+ and Ba2+ in a voltage-dependent manner. Rat peritoneal mast cells had a whole-cell conductance of only 10-30 pS, and the resting potential was close to zero. Sometimes discrete openings of channels were observed in the whole-cell configuration. When the Ca2+ concentration on the cytoplasmic side of the membrane was elevated, two types of channels with poor ion specificity appeared. A cation channel, observed at a Ca2+ concentration of approximately 1 microM, had a unit conductance of 30 pS. The other channel, activated at several hundred micromolar Ca2+, was anion selective and had a unit conductance of approximately 380 pS in normal Ringer solution and a bell-shaped voltage dependence. Antigenic stimulation did not cause significant changes in the ionic conductances in either cell type, which suggests that these cells use a mechanism different from ionic currents in stimulus-secretion coupling.
D000818:Animals; D001491:Basophils / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D004553:Electric Conductivity; D006636:Histamine Release; D007073:Immunoglobulin E / Q000276:immunology; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007942:Leukemia, Experimental / Q000503:physiopathology*; D008407:Mast Cells / Q000276:immunology / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology
D007473:Ion Channels; D007073:Immunoglobulin E; D012964:Sodium; D011188:Potassium; D002118:Calcium