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The determination that Angeli's salt may have clinical application as a nitrogen oxide donor for treatment of cardiovascular diseases such as heart failure has led to renewed interest in the mechanism and products of thermal decomposition of the salt under physiological conditions. Several mechanisms are evaluated experimentally and by quantum mechanical calculations to determine whether HNO is in fact released from Angeli's salt in neutral, aerobic solution.

A novel caged form of the highly reactive bioeffector molecule, nitroxyl (HNO) is described. Micromolar concentrations of prodrug iPrHN-N(O)[double bond]NO-C[H.sub.2]OAc (AcOM-IPA/NO) has exhibited more potent sarcomere shortening efforts relative to IPA/NO on ventricular myocytes isolated from wild-type mouse hearts, which has shown that AcOM-IPA/NO is a promising lead compound for the development of heart failure therapies.

Isopropylamine diazeniumdiolate, IPA/NO, the product of the reaction of isopropylamine and nitric oxide, NO, decomposes in a pH-dependent manner to afford nitroxyl, HNO in the pH range of 13 to above 5 and NO below pH 7. Studies using density functional theory, polarizable continuum solvation models and the high-accuracy CBS-QB3 method on the model component methylamine diazeniumdiolate predict a mechanism involving HNO production through decomposition of the unstable tautomer MeNN(super +)(O(super -))NHO(super -).

The photochemical properties of the ruthenium(II) porphyrins Ru(P)(NO)(ONO) were investigated by flash photolysis with time-resolved optical and time-resolved infrared spectral detection. Two primary photoproducts, Ru(P)(ONO) and Ru(P)(NO), were formed through nitric oxide photolabilization and nitrogen dioxide photolabilization, respectively. It was also found that there are at least two pathways that result in the formation of photoreaction intermediates.

Studies the synthesis and structural characterization of several ruthenium porphyrin nitrosyl complexes. Experimental procedure used; Results of the study.

Diazeniumdiolates, more commonly referred to as NONOates, have been extremely useful in the investigation of the biological effects of nitric oxide (NO) and related nitrogen oxides. The NONOate Angeli's salt (Na(2)N(2)O(3)) releases nitroxyl (HNO) under physiological conditions and exhibits unique cardiovascular features (i.e., positive inotropy/lusitropy) that may have relevance for pharmacological treatment of heart failure. In the search for new, organic-based compounds that release HNO, we examined isopropylamine NONOate (IPA/NO; Na[(CH(3))(2)CHNH(N(O)NO]), which is an adduct of NO and a primary amine. The chemical and pharmacological properties of IPA/NO were compared to those of Angeli's salt and a NO-producing NONOate, DEA/NO (Na[Et(2)NN(O)NO]), which is a secondary amine adduct. Under physiological conditions IPA/NO exhibited all the markers of HNO production (e.g., reductive nitrosylation, thiol reactivity, positive inotropy). These data suggest that primary amine NONOates may be useful as HNO donors in complement to the existing series of secondary amine NONOates, which are well-characterized NO donors.