POLAROGRAPHIC DETECTION OF NITRIC-OXIDE RELEASED FROM CARDIOVASCULAR COMPOUNDS IN AQUEOUS-SOLUTIONS

In order to detect the concentration of nitric oxide, known to be one of the biologically active principles of certain cardiovascular compou nds, a highly selective polarographic/amperometric device was used. Th e nitric oxide-releasing properties of sodium nitroprusside, nitroglyc erine, nicorandil, and the molsidomine metabolite, 3-morpholinosydnoni mine, were compared in the following cell-free experimental solutions in vitro: in Krebs-Henseleit solution with and without a sulfhydryl do nor, L-cysteine, in an acidic, reducing medium, and in Krebs-Henseleit solution with superoxide dismutase enzyme. Sodium nitroprusside relea sed similar concentrations of nitric oxide in Krebs-Henseleit solution and in the acidic, reducing medium. L-Cysteine inhibited the release of nitric oxide at physiological pH. In the presence of nitroglycerine , nitric oxide signals were detected in the acidic, reducing environme nt and in L-cysteine-rich Krebs-Henseleit solution but not in the abse nce of the sulfhydryl donor. Amperometric signals could not be detecte d after adding nicorandil in all the experimental conditions used. 3-M orpholinosydnonimine released nitric oxide only in the presence of the superoxide dismutase enzyme. Our results suggest that the polarograph ic electrode is able to detect the release of nitric oxide from sodium nitroprusside, nitroglycerine, and 3-morpholinosydnonimine in the abs ence of biological material. The present observations support the impo rtance of the chemical environment during the detection of nitric oxid e from donor compounds in the common in vitro bathing systems. (C) 199 8 Elsevier Science Inc.