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Nitric oxide (NO) donors produce NO-related activity when applied to biological systems. Among its diverse functions, NO has been implicated in vascular smooth muscle relaxation. Despite the great importance of NO in biological systems, its pharmacological and physiological studies have been limited due to its high reactivity and short half-life. In this review we will focus on our recent investigations of nitrosyl ruthenium complexes as NO-delivery agents and their effects on vascular smooth muscle cell relaxation. The high affinity of ruthenium for NO is a marked feature of its chemistry. The main signaling pathway responsible for the vascular relaxation induced by NO involves the activation of soluble guanylyl-cyclase, with subsequent accumulation of cGMP and activation of cGMP-dependent protein kinase. This in turn can activate several proteins such as K + channels as well as induce vasodilatation by a decrease in cytosolic Ca 2+ . Oxidative stress and associated oxidative damage are mediators of vascular damage in several cardiovascular diseases, including hypertension. The increased production of the superoxide anion (O 2 -) by the vascular wall has been observed in different animal models of hypertension. Vascular relaxation to the endogenous NO-related response or to NO released from NO deliverers is impaired in vessels from renal hypertensive (2K-1C) rats. A growing amount of evidence supports the possibility that increased NO inactivation by excess O 2 -may account for the decreased NO bioavailability and vascular dysfunction in hypertension.

Processing of materials in the form of ceramics normally involves several steps including calcination at a relatively low temperature for synthesis of the end-product powder and sintering at a high temperature for densification. The work we have been developing introduces a novel approach enabling synthesis plus sintering of materials in a single running experiment by using electric fields, ending with dense ceramics that display grains noticeably finer than in conventional processing. This new paradigm is fully illustrated with experiments conducted on amorphous CaCu 3 Ti 4 O 12 precursor powder, shown to experience, on heating, crystallization through intermediate phases, followed by chemical reaction leading to synthesis of the end-product powder, plus densification depending on field adjustment. The processing time and furnace temperature are considerably reduced, demonstrating that enhanced synthesis and sintering rates applied under field input. Similar results found in Bi 2/3 Cu 3 Ti 4 O 12 are also shown. The different factors that may contribute to this unique scenario, including Joule heating, defect generation, and reduction of free energy for nuclei formation promoted by the applied field, are briefly discussed. Overall, the findings we bring here are exclusive as they show an exploitable way that allows rapid processing of materials with good control over particle and grain coarsening.

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