RESUMO
Diazeniumdiolates (NONOates), among them a ciprofloxacin-diazeniumdiolate hybrid compound, were synthesized and the pH-, temperature- and structure-dependent liberation of nitric oxide (NO) was monitored by laser magnetic resonance spectroscopy (LMRS). The compounds induced a transient and reversible relaxation (EC(50) 8.3-150 nM) of pulmonary arteries independently from intact endothelium by stimulation of guanylyl cyclase (sGC). Increase in vascular cGMP was observed and blocking sGC with ODQ, an inhibitor of the NO-sensitive guanylyl cyclase, induced a rightward shift of the concentration-response curves. Repeated exposure did not show homologous desensitization. ADP-induced platelet aggregation (IC(50) = 0.15-3 microM, IC(50) for SNP: 2 microM) and collagen-induced aggregation were potently inhibited. Preincubation with ODQ also diminished these inhibitory effects.
Assuntos
Compostos Azo/farmacologia , Endotélio Vascular/metabolismo , Guanilato Ciclase/antagonistas & inibidores , Doadores de Óxido Nítrico/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Artéria Pulmonar/fisiologia , Vasodilatação/efeitos dos fármacos , Difosfato de Adenosina/farmacologia , Animais , Compostos Azo/síntese química , Colágeno/farmacologia , GMP Cíclico/metabolismo , Endotélio Vascular/efeitos dos fármacos , Lasers , Espectroscopia de Ressonância Magnética , Óxido Nítrico/metabolismo , Doadores de Óxido Nítrico/síntese química , Agregação Plaquetária/fisiologia , Inibidores da Agregação Plaquetária/síntese química , SuínosRESUMO
We describe a technique in which for the first time laser magnetic resonance spectroscopy (LMRS) is used online to monitor the release of nitric oxide from synthetic NO donors. LMRS is a spectroscopic method for selective, sensitive (to 1 ppb), and time-resolved NO gas detection in the far-infrared and midinfrared spectral regions. We used two partly novel sets of diazeniumdiolates, the first set derived from N,N-diethylamine (-->DEA-NO), piperidine ((-->PIPE-NO), 2-methylpiperidine (-->MEPIPE-NO), and 2-ethylpiperidine (-->EPIPE-NO) and the second set derived from 2-, 3-, and 4-piperidine carboxylic acids (-->PIPECO-NO, NIPECO-NO, ISONIPECO-NO). We monitored the acid-catalyzed NO liberation from these compounds as influenced by parameters such as pH, temperature, concentration, and molecular structure. PIPECO-NO turned out to be the fastest donor of the group. The 3- and 4-substituted isomer derivatives were only negligibly faster releasers than unsubstituted PIPE-NO, which on the other hand showed to be faster than the higher homologues MEPIPE-NO and EPIPE-NO. The results demonstrate that varying neighboring groups affect the functional diazeniumdiolate group differently. A vicinal carboxyl group increases and alkyl groups decrease the rate of NO release.