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1 Endotoxin E. Coli lipopolysaccharide (LPS)‐treatment in conscious, restrained rats increased plasma and urinary prostaglandin (PG) and nitric oxide (NO) production. Inducible cyclo‐oxygenase (COX‐2) and nitric oxide synthase (iNOS) expression accounted for the LPS‐induced PG and NO release since the glucocorticoid, dexamethasone inhibited both effects. Thus, LPS (4 mg kg⁻¹) increased the plasma levels of nitrite/nitrate from 14 ± 1 to 84 ± 7 μm within 3 h and this rise was inhibited to 35 ± 1 μm by dexamethasone. Levels of 6‐keto PGF_1α in the plasma were below the detection limit of the assay (< 0.2 ng ml⁻¹). However, 3 h after the injection of LPS these levels rose to 2.6 ± 0.2 ng ml⁻¹ and to 0.7 ± 0.01 ng ml⁻¹ after LPS in rats that received dexamethasone.

2 The induced enzymes were inhibited in vivo with selective COX and NOS inhibitors. Furthermore, NOS inhibitors, that did not affect COX activity …