Intracellular calcium signals in response to bradykinin in
individual neuroblastoma cells.
Coggan, Jay S., and Stuart H. Thompson.
Hopkins Marine Station and Department of Biological Sciences,
Stanford University, Pacific Grove, Ca 93950
APStracts 2:0230C, 1995.
The modulation of cytoplasmic calcium, (Cai), by bradykinin (Bk) was
studied in single N1E-115 murine neuroblastoma cells using the Ca
indicator fura-2. Increases in (Cai) in response to Bk were mediated
by the B2 receptor subtype. Responses to high concentrations of Bk (1
- 100 nM) were homogeneous and characterized by a rapidly rising
transient that decayed to baseline in the continued presence of
agonist with a half-time of 15 seconds. Responses to low
concentrations of Bk (100 - 500 pM) were more heterogeneous, with
longer latencies and often with oscillations. Pretreatment with
thapsigargin for 20 minutes prevented the Ca response showing that
the Ca change results from intracellular Ca release. Removal of
external Ca had little effect on the response to Bk, indicating that
the agonist does not activate Ca influx. The extent of Ca release and
refilling after Bk was tested with ionomycin. A saturating dose of Bk
(20 nM) mobilizes greater than 90% of stored Ca within 30 seconds and
this is replaced slowly. Replacement of external Na by N-methyl-D
-glucamine (NMG) to block Na/Ca exchange affected the Ca response,
causing decreases in latency and in the period of Ca oscillations and
increases in overall duration and peak amplitude of the response.
Received 31 October 1994; accepted in final form 10 April 1995.
APS Manuscript Number C642-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.