Neutrophil Secretion Induced by an Intracellular Ca2+ Rise and Followed by Whole-Cell Patch-Clamp Recordings Occurs Without any Selective Mobilization of Different Granule Populations

摘要

We have investigated calcium-induced secretion in humanneutrophils, using a whole-cell patch-clamp technique.Mobilization of subcellular granules to the cell membrane wasfollowed as the change in membrane capacitance (ΔCm).Both the magnitude and the kinetics of the response differedbetween low and high concentrations of Ca2+. A sustainedsecretion following a short lag phase was induced by highconcentrations of Ca2+ (100 μM and higher). Astable plateau was reached after 5–7 minutes at ΔCmvalues corresponding to values expected after all specific as wellas azurophil granules have been mobilized. Capacitance values ofthe same magnitude could be obtained also at lower Ca2+ concentrations, but typically no stable plateau was reached withinthe measuring time. In contrast to previous studies, we wereunable to detect any pattern of secretion corresponding to adistinct submaximal response or selective mobilization of granulesubsets specified by their Ca2+-sensitivity.