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M O Lonchampt

Publications and source records attributed to M O Lonchampt.

26 records · Page 2Linked to original sources
PubMed1987

Down-regulation of atrial natriuretic factor receptors and correlation with cGMP stimulation in rat cultured vascular smooth muscle cells.

The relationship between the binding of 125I-labeled rat ANF and the responsiveness in cGMP production of ANF receptors were examined in cultured rat thoracic smooth muscle cells after preexposure with the peptide. Binding assay of 125I-labeled ANF showed a specific, reversible and saturable binding with a KD value of 3.1 +/- 0.3 10(-10) M and a maximum binding (Bmax) of 240 +/- 30 fmol/10(6) cells. Pretreatment of the cells with increasing concentrations of unlabeled ANF (10(-9) M to 10(-7) M) resulted in a dose-dependent decrease of the number of binding sites without a change in the affinity. This effect was clearly associated with a desensitization of ANF-induced cGMP production.

Animals↗
PubMed1983

Evidence of leukotriene B4 biosynthesis in epithelial lens cells.

Metabolism of sodium (14C)-arachidonate by bovine epithelial lens cells was studied in culture. The cells converted arachidonic acid into a major product whose formation was not inhibited by aspirin, a cyclo-oxygenase inhibitor, but was suppressed by nordihydroguaiaretic acid, a lipoxygenase inhibitor and by dexamethasone. This metabolite co-migrated with leukotriene B4 in thin layer chromatography and high pressure liquid chromatography. These data represent the first evidence for a lipoxygenase product in the lens. LTB4 could play an important role in the physiopathology of this organ.

Animals↗
PubMed1979

The effect of high glucose concentration on the proliferation and the synthesis of lipids in endothelial cells in culture.

Influence of glucose concentration on growth and lipid synthesis was investigated in human endothelial cells in culture. The biosynthesis of lipids from acetate and glucose was present in endothelial cells, but a high glucose level in the culture medium failed to modify lipid synthesis. Neosynthesis in the lipidic fraction in the medium is higher when precursor is acetate compared to glucose.

Acetates↗
PubMed1975

Lens glycoproteins: biosynthesis in cultured epithelial cells of bovine lens.

1. Radioactivity from [3H]glucosamine is rapidly incorporated into cellular fractions of lens epithelial cells cultured in vitro. The incorporated isotope appears largely in glycoproteins of the cell surface that are exposed to trypsin and are released into a soluble form by proteolysis of intact cells. Glycoproteins are also secreted by cultured cells and can be recovered in the culture fluids. Sodium dodecysulphate-polyacrylamide gell electrophoresis shows that a range of glycoproteins with apparent molecular weights from approximately 14000 to 120000 are present. The relationships of these glycoproteins to collagen and the non-collagenous glycoproteins of lens basement membranes are discussed. 2. A plasma membrane fraction obtained from non-trypsinised lens epithelial cells contains one major glycoprotein of apparent molecular weight 120000. A major non-glycosylated polypeptide of molecular weight about 38000 detectable by Bloemendal et al. (1972) in plasma membranes of differentiated lens fibre cells was not prominent in lens epithelial cell membranes. 3. Examination of lens basement membranes extracted in various ways failed to reveal major glycoproteins of low molecular weight. Higher molecular weight glycoproteins, some of them related to collagen, were present.

Animals↗
PubMedDate not supplied

Endothelin receptor regulation by endothelin synthesis in vascular smooth muscle cells: effects of dexamethasone and phosphoramidon.

One of the major biological effects of the endothelium-derived peptide endothelin-1 (ET-1) is its receptor-mediated constrictive action on vascular smooth muscle. In this study, we have examined the effects on the ET-1 pathway of 18 h exposure at 37 degrees C of cultured rat aortic smooth muscle cells to dexamethasone (DEX) and phosphoramidon. ET-1 synthesis was evaluated by radioimmunoassay, ET-1 binding characteristics were determined with [125I]iodo-ET-1, and ET-1-induced intracellular calcium mobilization was measured using fura-2-loaded cells. DEX (100 nM) led to a 2- to 3-fold-increase of ET-1 production, it down-regulated ET-1 receptors and reduced ET-1-stimulated calcium mobilization by 70%. In contrast, phosphoramidon (100 microM) inhibited ET-1 production by 60%, up-regulated ET-1 receptors and potentiated ET-1-induced calcium mobilization by 75%. These results indicate that the regulatory effects of DEX and phosphoramidon on ET-1 receptors are mediated via ET-1 production by the cells. This suggests an autocrine control of ET-1 receptors by endogenous ET-1 synthesis in vascular smooth muscle cells.

Animals↗