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.
We have investigated calcium-induced secretion in human neutrophils, using a whole-cell patch-clamp technique. Mobilization of subcellular granules to the cell membrane was followed as the change in membrane capacitance (deltaC(m)). Both the magnitude and the kinetics of the response differed between low and high concentrations of Ca(2+). A sustained secretion following a short lag phase was induced by high concentrations of Ca(2+) (100 microM and higher). A stable plateau was reached after 5-7 minutes at deltaC(m) values corresponding to values expected after all specific as well as azurophil granules have been mobilized. Capacitance values of the same magnitude could be obtained also at lower Ca(2+) concentrations, but typically no stable plateau was reached within the measuring time. In contrast to previous studies, we were unable to detect any pattern of secretion corresponding to a distinct submaximal response or selective mobilization of granule subsets specified by their Ca(2+)-sensitivity.
Granfeldt
Daniel
D
The Phagocyte Research Laboratory, Department of Rheumatology and Inflammation Research, Göteborg University, Göteborg, Sweden.
Harbecke
Olle
O
Björstad
Ase
A
Karlsson
Anna
A
Dahlgren
Claes
C