Nitric oxide-loaded echogenic liposomes for treatment of vasospasm following subarachnoid hemorrhage.

Delayed cerebral vasospasm following subarachnoid hemorrhage causes severe ischemic neurologic deficits leading to permanent neurologic dysfunction or death. Reduced intravascular and perivascular nitric oxide (NO) availability is a primary pathophysiology of cerebral vasospasm. In this study, we evaluated NO-loaded echogenic liposomes (NO-ELIP) for ultrasound-facilitated NO delivery to produce vasodilation for treatment of vasospasm following subarachnoid hemorrhage. We investigated the vasodilative effects of NO released from NO-ELIP both ex vivo and in vivo. Liposomes containing phospholipids and cholesterol were prepared, and NO was encapsulated. The encapsulation and release of NO from NO-ELIP were determined by the syringe/vacuum method and ultrasound imaging. The ex vivo vasodilative effect of NO-ELIP was investigated using rabbit carotid arteries. Arterial vasodilation was clearly observed with NO-ELIP exposed to Doppler ultrasound whereas there was little vasodilative effect without exposure to Doppler ultrasound in the presence of red blood cells. Penetration of NO into the arterial wall was determined by fluorescent microscopy. The vasodilative effects of intravenously administered NO-ELIP in vivo were determined in a rat subarachnoid hemorrhage model. NO-ELIP with ultrasound activation over the carotid artery demonstrated effective arterial vasodilation in vivo resulting in improved neurologic function. This novel methodology for ultrasound-controlled delivery of NO has the potential for therapeutic treatment of vasospasm following subarachnoid hemorrhage. This ultrasound-controlled release strategy provides a new avenue for targeted bioactive gas and therapeutic delivery for improved stroke treatment.

Nitric oxide scavenging by red cell microparticles.

Red cell microparticles form during the storage of red blood cells and in diseases associated with red cell breakdown and asplenia, including hemolytic anemias such as sickle cell disease. These small phospholipid vesicles that are derived from red blood cells have been implicated in the pathogenesis of transfusion of aged stored blood and hemolytic diseases, via activation of the hemostatic system and effects on nitric oxide (NO) bioavailability. Red cell microparticles react with the important signaling molecule NO almost as fast as cell-free hemoglobin, about 1000 times faster than red-cell-encapsulated hemoglobin. The degree to which this fast reaction with NO by red cell microparticles influences NO bioavailability depends on several factors that are explored here. In the context of stored blood preserved in ADSOL, we find that both cell-free hemoglobin and red cell microparticles increase as a function of duration of storage, and the proportion of extra erythrocytic hemoglobin in the red cell microparticle fraction is about 20% throughout storage. Normalized by hemoglobin concentration, the NO-scavenging ability of cell-free hemoglobin is slightly higher than that of red cell microparticles as determined by a chemiluminescence NO-scavenging assay. Computational simulations show that the degree to which red cell microparticles scavenge NO will depend substantially on whether they enter the cell-free zone next to the endothelial cells. Single-microvessel myography experiments performed under laminar flow conditions demonstrate that microparticles significantly enter the cell-free zone and inhibit acetylcholine, endothelial-dependent, and NO-dependent vasodilation. Taken together, these data suggest that as little as 5 µM hemoglobin in red cell microparticles, an amount formed after the infusion of one unit of aged stored packed red blood cells, has the potential to reduce NO bioavailability and impair endothelial-dependent vasodilation.

Endothelium-dependent vasodilatation effects of the essential oil from Fructus alpiniae zerumbet (EOFAZ) on rat thoracic aortic rings in vitro.

Fructus Alpiniae Zerumbet (FAZ) is an herb widely used to treat vascular disorders in Guizhou province, China, the essential oil has been identified as one of it vasodilation effect active components, and especial, the composition was significantly difference from the leaves. Vasodilation effects and mechanism of essential oil from FAZ (EOFAZ) were investigated. The EOFAZ showed significant vasodilation effect on endothelium-with rat thoracic aortic rings preincubated with norepinephrine (NE, 1.0µM) or KCl (60mM) in a concentration-dependent manner (1.14-72.96µg/ml). The non-selective nitric oxide synthase inhibitor l-NAME, as well as the soluble guanylate cyclase inhibitor MB, attenuated the relaxation of EOFAZ in endothelium-intact rat thoracic aortic rings. However, there were not significantly affected the vasodilation effects pretreated with cyclooxygenase inhibition by indomethacin (Indo) or ß-noradrenergic inhibition by propranolol (Prop). The present results first demonstrated that vasodilation effect of EOFAZ depending upon the endothelium and concentration, and the mechanism involvement of NOS-cGMP system. In contrast, prostacyclin and ß-adrenoceptor may not be associated with EOFAZ-induced vasorelaxation.

Endothelium-dependent vasodilator and antioxidant properties of a novel enzymatic extract of grape pomace from wine industrial waste.

The aim of the present study was to evaluate the vascular effects of an enzymatic extract of grape pomace (GP-EE) on isolated arteries, focusing our attention on endothelium-derived relaxation and on its antioxidant properties. Grape pomace derived from wine making was extracted by an enzymatic process and its composition of polyphenols was evaluated by HPLC and ESI-MS/MS, detecting kaempferol, catechin, quercetin and procyanidins B1 and B2, trace levels of resveratrol and tracing out gallocatechin and anthocyanidins. GP-EE induced endothelium- and NO-dependent vasodilatation of both rat aorta and small mesenteric artery (SMA) segments and reduced Phe-induced response in aortic rings. Both ORAC and DPPH assays confirmed antioxidant scavenging properties of GP-EE, which also prevented O(2)(·-) production (assessed by DHE fluorescence) and contraction elicited by ET-1. These results provide evidence that GP-EE possesses interesting antioxidant and protective vascular properties and highlight the potential interest of this extract as a functional food.

Relaxant activity of 2-(substituted phenyl)-1H-benzimidazoles on isolated rat aortic rings: design and synthesis of 5-nitro derivatives.

The relaxant activity of 2-(o, p-substituted phenyl)-1H-benzimidazole derivatives with various 5- and 6-position substituents (-H, -CH3, -NO2, -CF3), namely 1-7, was recorded using the in vitro rat aorta ring test. Compounds 3 and 6 [2-(5-nitro-1H-benzimidazol-2-yl)phenol and 2-(4-methoxyphenyl)-5-nitro-1H-benzimidazole] were prepared using a short route, and were the most potent compounds of the series, showing IC50 value of 0.95 and 1.41 (with endothelium) and 2.01 and 3.61 microM (without endothelium), respectively. Studying further structure-activity relationships through the use of bioisosteric substitution in these benzimidazole derivatives should provide novel vasorelaxant leads and possibly against hypertensive diseases.

Mechanisms of endothelial dysfunction: clinical significance and preventive non-pharmacological therapeutic strategies.

Endothelium-derived NO is not only a potent vasodilator but also inhibits platelet aggregation, vascular smooth muscle cell migration and proliferation, monocyte adhesion and adhesion molecule expression, thus protecting the vessel wall against the development of atherosclerosis. Cardiovascular risk factors are associated with an imbalance of the redox equilibrium towards oxidative stress and, therefore, impair the integrity of the endothelium, leading to endothelial activation which involves blunted endothelium-dependent vasodilation (vasodilator dysfunction) as well as inflammatory processes extending to the milieu within the whole vasculature, making plaques prone to rupture. In prospective studies endothelial dysfunction is associated with increased incidence of cardiovascular events. Thus, the prevention of endothelial dysfunction can determine a strong advantage in the clinical outcome of patients with cardiovascular risk factors. Several non-pharmacological interventions can prevent endothelial dysfunction or improve impaired endothelium-dependent vasodilation. Probably the most effective non-pharmacological measure is represented by aerobic physical activity, which can reduce production of oxidative stress associated to increasing age. Moreover, physical activity can improve endothelial dysfunction even in patients with cardiovascular risk factors such as essential hypertension. In addition several other approaches, including vitamin and fish oil supplementation, or tea and red wine consumption, can lead to an improvement of endothelium-dependent vasodilation, possibly by a restoration of NO availability. It is worth noting that most of non-pharmacological measures act by preventing or reducing oxidative stress.