LIPOPOLYSACCHARIDE INDUCES CA2-INDEPENDENT NITRIC-OXIDE SYNTHASE ACTIVITY IN RAT GASTRIC-MUCOSAL CELLS()

Ca2+-independent nitric oxide synthase was detected in gastric mucosal cells isolated from rats injected 4 h previously with Escherichia col i lipopolysaccharide (3 mg/kg i.v.). Induced nitric oxide synthase was located in an elutriated cell fraction of intermediate size which con tained epithelial cells, but was absent from the parietal cell fractio n. Administration of dexamethasone (2 mg/kg i.p.) 1 h before lipopolys accharide inhibited the appearance of Ca2+-independent nitric oxide sy nthase, and prevented the observed reduction in cell viability (trypan blue exclusion). Ca2+-independent nitric oxide synthase activity can thus be induced in certain cells of the gastric mucosa, and may contri bute to gastric pathologies where there is activation of the immune sy stem.