Secretory responses of @entity35 peritoneal mast cells to high intracellular XXXX .

@entity3007 @entity141 @entity29576 @entity1360 @entity460 @entity35
The patch-clamp technique was used to investigate the secretory responses of @entity35 peritoneal mast cells at various intracellular @entity460 concentrations ([ @entity141 ]i). When @entity460 was introduced into the cell with pipette-loaded @entity29576 , elevation of [ @entity141 ]i into the range 1-10 microM induced membrane capacitance increases indicative of exocytosis in a concentration-dependent manner. At higher concentrations a decrease of the response was observed. Cells that were exposed to micromolar [ @entity141 ]i underwent morphological alterations resulting in swelling, which is indicative of cytoskeletal alterations. The presence of @entity29576 (4 mM) strongly inhibited secretion induced by @entity3007 -gamma-S, thus hampering the contribution of G-protein-mediated stimulation. Application of the @entity141 ionophore @entity1360 resulted in transient increases in [ @entity141 ]i which were parallelled by @entity141 -dependent secretion. Effective buffering of the cytosolic @entity460 level below 1 microM abolished the secretory response. Our results show that an increase in [ @entity141 ]i can trigger secretion, but only if it is high and sustained. During physiological stimulation, however, secretion proceeds at [ @entity141 ]i below 1 microM. It is, therefore, concluded that mast cell degranulation under physiological conditions is not simply a result of an increase in [ @entity141 ]i, but that other second messenger systems in conjunction with @entity460 act synergistically in order to ensure fast and efficient secretion.
