Vasodilatory properties of mono-L-arginine-containing compounds

Benzoyl derivatives of L-arginine, unlike arginine, elicited relaxation of pre-contracted rat aortic rings in a concentration dependent manner. The most potent relaxing agent was N-alpha-benzoyl-L-arginine ethyl ester. The relaxation was abolished by methylene blue, but not by indomethacin. When incubated with rat aortic rings, the benzoyl derivatives exhibited colorimetric reactions characteristic of citrulline and nitrite ion. This indicates the presence of a peptidyl arginine deiminase like activity in rat aorta. Citrulline had no vasodilatory property. The other product of the iminase reaction is ammonia which through oxygenase pathway may generate nitric oxide, the proposed endothelium derived relaxing factor(EDRF). Our results suggest that an as yet unidentified arginine derivative from the endothelium may be the biological precursor of EDRF.