Premium
Differentiation of the human monocytic cell line U937 results in an upregulation of the calcium release‐activated current, ICRAC.
Author(s) -
Floto R A,
Mahaut-Smith M P,
Allen J M,
Somasundaram B
Publication year - 1996
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1996.sp021597
Subject(s) - u937 cell , thapsigargin , intracellular , bapta , chemistry , biophysics , downregulation and upregulation , calcium , patch clamp , cell culture , microbiology and biotechnology , fura 2 , calcium in biology , biochemistry , biology , cytosol , apoptosis , receptor , genetics , organic chemistry , gene , enzyme
1. Single cell fura‐2 fluorescence measurements and whole‐cell patch clamp recordings were used to investigate the effects of macrophage‐like differentiation, induced by dibutyryl cAMP (dbcAMP), on Ca2+ influx triggered by Ca2+ store depletion in the human monocytic cell line, U937. 2. In differentiated cells, the rise in intracellular [Ca2+] following store depletion by thapsigargin (TG) in nominally Ca(2+)‐free solution was 94% greater and the [Ca2+]i rise on subsequent re‐addition of external Ca2+ (2 mM) was 292% greater than in undifferentiated cells. 3. Under conditions where [Ca2+]i was buffered by BAPTA, TG‐induced store depletion failed to activate a detectable inward Ca2+ current in undifferentiated U937 cells. Under identical conditions, store depletion of differentiated U937 cells generated an inwardly rectifying Ca(2+)‐selective current which showed no reversal from ‐140 to +30 mV and was blocked by 1 microM external La3+; characteristics of the calcium release‐activated Ca2+ current (ICRAC) identified in other cells. 4. We conclude that U937 cells show a differentiation‐dependent upregulation of a store‐mediated Ca2+ entry pathway, identified as ICRAC, which is not correlated with the small associated increase in the size of TG‐sensitive Ca2+ pools.