NO-donors, part 9 [1]: diazeniumdiolates inhibit human platelet aggregation and induce a transient vasodilatation of porcine pulmonary arteries in accordance with the NO-releasing rates

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 (EC50 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 (IC50 = 0.15-3 μM, IC50 for SNP: 2 μM) and collagen-induced aggregation were potently inhibited. Preincubation with ODQ also diminished these inhibitory effects.