Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cell Degranulation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1986

Rat serosal mast cell degranulation mediated by chymase, an endogenous secretory granule protease: active site-dependent initiation at 1 degree C.

Exposure at 37 degrees C of rat serosal mast cells (RSMC) to chymase, an endogenous secretory granule serine protease, results in exocytosis as determined by the release of another secretory granule enzyme, beta-hexosaminidase. Chymase-mediated RSMC degranulation does not occur at 1 degree C; however, exposure of RSMC to chymase at 1 degree C followed by the removal of buffer and the resuspension of the cells in buffer alone at 37 degrees C results in exocytosis equivalent to that obtained by direct exposure of RSMC to chymase at 37 degrees C. Maximal chymase-mediated RSMC degranulation at 37 degrees C is Ca2+-dependent and Mg2+-independent. The dose-dependent degranulation-inducing interaction of chymase and alpha-chymotrypsin with RSMC at 1 degree C is Ca2+-independent, whereas subsequent exocytosis at 37 degrees C in new buffer without added enzyme still requires Ca2+. Specific binding of 125I-labeled alpha-chymotrypsin to RSMC does not occur at 1 degree C, implying that the inducing action of chymase is not a simple ligand-receptor binding. The enzyme inhibitors diisopropyl fluorophosphate and lima bean trypsin inhibitor inhibit subsequent exocytosis at 37 degrees C only if they are added within the first 10 min of the interaction of RSMC and chymase at 1 degree C, implying that an active site-dependent inducing event occurs between RSMC and chymase at 1 degree C. Thus, chymase-induced coupled activation-secretion can be divided into a cation- and temperature-independent initiation phase, which is dependent on the active site of exogenously added chymase and a subsequent temperature-dependent and calcium-augmented cellular secretion phase.

Animals↗
PubMed1996

Colonic motor response to IgE-mediated mast cell degranulation in the Hooded-Lister rat.

After challenge of sensitized individuals, food protein-induced colonic anaphylaxis may contribute to the symptom of diarrhoea. The aim of this study was to characterize the effect of food protein-induced anaphylaxis on colonic circular muscle in vitro, identify the mediators involved, and then evaluate the effect of antigen challenge on colonic transit in vivo. Hooded-Lister rats were sensitized by intraperitoneal injection of egg albumin and controls were sham-sensitized with saline. Rings of distal colonic tissue were suspended in standard tissue baths (mucosa intact) and circular muscle contractility was measured in response to antigen or other agents on day 14. In conscious animals, Na2(51)CrO4 was instilled alone, or with antigen, via proximal colostomy and the geometric centre of distribution of51Cr calculated. Following antigen challenge, a contractile response occurred only in animals that were sensitized (specific IgE antibody levels > or = 1:64), and was specific for the sensitizing antigen. Mast cell involvement was suggested when (1) concanavalin A (a degranulator of both mucosal and connective tissue mast cells) mimicked the antigen-induced response, and (2) Ag-induced contraction was significantly inhibited by mast cell stabilizers. The Ag-induced response was significantly and independently inhibited by a lipo-oxygenase enzyme inhibitor and by LTD4 and platelet activating factor receptor antagonists. The antigen-induced response was resistant to histamine and 5-hydroxytryptamine receptor antagonists, indomethacin, atropine and tetrodotoxin. The geometric centre of distribution of 51Cr was significantly more distal in sensitized animals challenged with antigen rather than placebo, and only sensitized animals challenged with antigen developed diarrhoea. These results suggest that colonic antigen challenge of sensitized rats is associated with IgE-mediated mast cell activation, the release of membrane derived mediators which, in vitro, act directly on smooth muscle to induce contraction, and in vivo result in an increased rate of aboral transit and diarrhoea.

Albumins↗
PubMed1977

The site of action of the histamine releaser compound 45/80 in causing mast cell degranulation.

A primary amine analog of compound 48/80 (nor-48/80) was purified and attached to Sepharose beads through an albumin link. Suspensions of rat peritoneal cells were passed over the beads in an affinity chromatography column, and the proportion of the mast cells that was retained by the beads was determined. Sixty-seven percent of the mast cells were found to be retained by the column, indicating the existence of a binding site for nor-48/80 on the exterior of mast cells. The beads were larger than the cells, and hence precluded the entry of the nor-48/80 into the cells. Neither the Sepharose beads nor the albumin link was responsible for this amount of binding because control beads without nor-48-80 retained only 22% of the mast cells. Mast cells incubated with large quantities of the beads in a batch procedure released up to 53% of the mast cell histamine, whereas control beads without the polymer released only 18%. This release could not be attributable to soluble nor-48/80 because only trace amounts of radioactive nor-48/80 were released from beads soaked overnight, and these supernatants released insignificant amounts of histamine when incubated with mast cells. These studies indicate the presence of a receptor for 48/80 on the mast cell membrane which can trigger histamine release.

Animals↗