Increased urinary nitrate excretion in rats with adjuvant arthritis.

<bold>Objectives: </bold>In rats with adjuvant arthritis measurements were taken of the urinary excretion of nitrate, reflecting endogenous nitric oxide (NO) formation, and cyclic guanosine monophosphate (cGMP).<bold>Methods: </bold>Urinary nitrate was determined by gas chromatography, cGMP by radioimmunoassay.<bold>Results: </bold>A significant (p < 0.001), more than three fold increase of urinary nitrate excretion was found in rats 20 days after induction of adjuvant arthritis compared with non-arthritic rats. There was no significant difference in urinary cGMP excretion between arthritic rats and control animals.<bold>Conclusion: </bold>The data suggest that the dramatic increase of urinary nitrate excretion is due to increase of NO synthesis by the inducible form of NO synthase. [ABSTRACT FROM AUTHOR]