AJP - Cell Physiology, Vol 263, Issue 4 C736-C742, Copyright © 1992 by American Physiological Society
Substance P induces whole cell current transients in RBL-2H3 cells
J. Janiszewski, J. Bienenstock and M. G. Blennerhassett
Department of Pathology, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada.
To investigate the basis of interactions between nerves and mast cells, we
tested the actions of the neuropeptide substance P (SP) on whole cell
current characteristics of RBL-2H3 cells (homologous to mucosal mast
cells). Control RBL cells showed a K(+)-dependent inwardly rectified
current. SP (10(-6) M) caused transient, frequently repetitive increases in
current amplitude, which at a membrane potential (Vm) of -80 mV rose by
-1,020.0 +/- 223.4 pA after SP application compared with -6.8 +/- 1.7 pA
for control. This response was characterized by a lag phase of 102 +/- 16
s. Seventeen percent of cells showed spontaneous transients in the current
amplitude from the beginning of the recording. After SP administration, the
amplitude of these transients increased by 6.3 +/- 2.0-fold. Responses to
SP were mimicked by the application of ionomycin. For both SP and
ionomycin, there was a dose dependency of the lag phase. Removal of
extracellular calcium abolished the response for 10(-6) M SP but not for
6.6 x 10(-6) M ionomycin. During current transients, the whole cell current
had both inward and outward rectified components with the zero current Vm
shifted from -87.3 +/- 3.2 mV at control to -10.8 +/- 1.7 mV. We compare
the SP-evoked current responses in mucosal-type mast cells with those
described in connective tissue type.
