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 coli lipopolysaccharide (3 mg/kg i.v.). Induced nitric oxide synthase was located in an elutriated cell fraction of intermediate size which contained epithelial cells, but was absent from the parietal cell fraction. Administration of dexamethasone (2 mg/kg i.p.) 1 h before lipopolysaccharide inhibited the appearance of Ca²⁺-independent nitric oxide synthase, 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 contribute to gastric pathologies where there is activation of the immune system.