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Title: Role of membrane depolarization and extracellular calcium in increased complement receptor expression during neutrophil (PMN) activation

During PMN activation the surface expression of receptors (R) for C3b and C3bi increases rapidly. This is necessary for optimal cell adhesion, migration, and phagocytosis. Following stimulation with fMLP or LTB-4, the increased expression of C3bR depends only on the Ca/sup + +/ released from intracellular stores and is not inhibited by 5mM EDTA, while the increase in C3biR also requires extracellular Ca/sup + +/. CR expression also increases when the PMN are depolarized with 140 mM K/sup +/, but with this stimulus, EDTA inhibits C3bR by 67% and C3biR 100%, suggesting that intracellular Ca/sup + +/ stores may not be released. Pertussis toxin caused dose-dependent inhibition of both CR responses to fMLP and also inhibited the increases in both CR induced by K/sup +/. Membrane depolarization (monitored by di-O-C5 fluorescence) due to fMLP was similarly inhibited by toxin but the depolarization due to K/sup +/ was not. The dose of phorbol myristate acetate that maximally increased CR expression, 0.1 ng/ml, did not depolarize the membrane. These results suggest that membrane depolarization is neither necessary nor sufficient for increased CR expression. A Ca/sup + +/ and GTP binding protein-dependent enzyme such as phospholipase C is necessary to the amplify initialmore » signals generated either by release of Ca/sup + +/ stores or by opening voltage dependent Ca/sup + +/ channels following membrane depolarization.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
6896992
Report Number(s):
CONF-8604222-
Journal ID: CODEN: FEPRA
Resource Type:
Conference
Resource Relation:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States); Journal Volume: 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
Research Org:
Case Western Reserve Univ., Cleveland, OH
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; CALCIUM COMPOUNDS; MEMBRANE TRANSPORT; CELL MEMBRANES; DEPOLARIZATION; NEUTROPHILS; ADHESION; PHAGOCYTOSIS; PHORBOL ESTERS; BIOLOGICAL EFFECTS; DOSE-RESPONSE RELATIONSHIPS; LIPASE; POTASSIUM COMPOUNDS; RECEPTORS; TOXINS; ALKALI METAL COMPOUNDS; ALKALINE EARTH METAL COMPOUNDS; ANTIGENS; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BODY FLUIDS; CARBOXYLESTERASES; CARCINOGENS; CELL CONSTITUENTS; ENZYMES; ESTERASES; ESTERS; HYDROLASES; LEUKOCYTES; MATERIALS; MEMBRANE PROTEINS; MEMBRANES; ORGANIC COMPOUNDS; PROTEINS; TOXIC MATERIALS 560300* -- Chemicals Metabolism & Toxicology