[Toxicity and hypotensive effect of L-arginine oxoborolidinone and its modulation by methylene blue. Comparison with L-arginine, nitrite, and nitrate].

Nitric oxide is synthesized by constitutive oxide nitric synthase from the guanidine group of L-arginine. L-arginine, oxoborolidinone of L-arginine, nitrite and nitrate showed dose-dependent hypotensive effects after injection via the femoral vein in Wistar rats. The hypotensive effects were shifted to the right after treatment with methylene blue, which is a synthetic phenothiazine inhibitor of guanylate cyclase. Oxoborolidinone of L-arginine had high hypotensive effects with an effective half dose of 10 eta moles kg-1 and of mumoles kg-1 for methylene blue. Methylene blue also attenuated the toxic effects of all the tested compounds.