In retrospect, basic research in the fields of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) during the past two decades appears to have followed a logical course, beginning with the findings that NO and cGMP are vascular smooth muscle relaxants, that nitroglycerin relaxes smooth muscle by metabolism to NO, progressing to the discovery that mammalian cells synthesize NO, and finally the revelation that NO is a neurotransmitter mediating vasodilation in specialized vascular beds. A great deal of basic and clinical research on the physiologic and pathophysiologic roles of NO in cardiovascular function has been conducted since the discovery that endothelium-derived relaxing factor (EDRF) is NO. The new knowledge on NO should enable investigators in this field to develop novel and more effective therapeutic strategies for the prevention, diagnosis, and treatment of numerous cardiovascular disorders. The goal of this review was to highlight the early research that led to our current understanding of the pathophysiologic role of NO in cardiovascular medicine. Furthermore, we discussed the possible mechanism of some drugs interfering with NO signaling cascade.

Adenoviruses are used extensively as gene transfer agents, both experimentally and clinically. However, targeting of liver cells by adenoviruses compromises their potential efficacy. In cell culture, the adenovirus serotype 5 fiber protein engages the coxsackievirus and adenovirus receptor (CAR) to bind cells. Paradoxically, following intravascular delivery, CAR is not used for liver transduction, implicating alternate pathways. Recently, we demonstrated that coagulation factor (F)X directly binds adenovirus leading to liver infection. Here, we show that FX binds to the Ad5 hexon, not fiber, via an interaction between the FX Gla domain and hypervariable regions of the hexon surface. Binding occurs in multiple human adenovirus serotypes. Liver infection by the FX-Ad5 complex is mediated through a heparin-binding exosite in the FX serine protease domain. This study reveals an unanticipated function for hexon in mediating liver gene transfer in vivo.

To determine whether oxidized LDL enhances atherogenesis by promoting monocyte recruitment into the vascular intima, we investigated whether LDL accumulation and oxidation precede intimal accumulation of monocytes in human fetal aortas (from spontaneous abortions and premature newborns who died within 12 h; fetal age 6.2 Ϯ 1.3 mo). For this purpose, a systematic assessment of fatty streak formation was carried out in fetal aortas from normocholesterolemic mothers ( n ϭ 22), hypercholesterolemic mothers ( n ϭ 33), and mothers who were hypercholesterolemic only during pregnancy ( n ϭ 27). Fetal plasma cholesterol levels showed a strong inverse correlation with fetal age ( R ϭ Ϫ 0.88, P Ͻ 0.0001). In fetuses younger than 6 mo, fetal plasma cholesterol levels correlated with maternal ones ( R ϭ 0.86, P ϭ 0.001), whereas in older fetuses no such correlation existed. Fetal aortas from hypercholesterolemic mothers and mothers with temporary hypercholesterolemia contained significantly more and larger lesions (758,651 Ϯ 87,449 and 451,255 Ϯ 37,448 m 2 per section, respectively; mean Ϯ SD) than aortas from normocholesterolemic mothers (61,862 Ϯ 9,555 m 2 ; P Ͻ 0.00005). Serial sections of the arch, thoracic, and abdominal aortas were immunostained for recognized markers of atherosclerosis: macrophages, apo B, and two different oxidation-specific epitopes (malondialdehyde-and 4-hydroxynonenal-lysine). Of the atherogenic sites that showed positive immunostaining for at least one of these markers, 58.6% were established lesions containing both macrophage/foam cells and oxidized LDL (OxLDL). 17.3% of all sites contained only native LDL, and 13.3% contained only OxLDL without monocyte/ macrophages. In contrast, only 4.3% of sites contained isolated monocytes in the absence of native or oxidized LDL. In addition, 6.3% of sites contained LDL and macrophages but few oxidation-specific epitopes. These results demonstrate that LDL oxidation and formation of fatty streaks occurs already during fetal development, and that both phenomena are greatly enhanced by maternal hypercholesterolemia. The fact that in very early lesions LDL and Ox-LDL are frequently found in the absence of monocyte/macrophages, whereas the opposite is rare, suggests that intimal LDL accumulation and oxidation contributes to monocyte recruitment in vivo. ( J. Clin. Invest. 1997. 100:2680-2690.)

Our results suggest that maternal hypercholesterolaemia during pregnancy induces changes in the fetal aorta that determine the long-term susceptibility of children to fatty-streak formation and subsequent atherosclerosis. If so, cholesterol-lowering interventions in hypercholesterolaemic mothers during pregnancy may decrease atherogenesis in children.

Background-Atherosclerotic renovascular disease may augment deterioration of renal function and ischemic nephropathy compared with other causes of renal artery stenosis (RAS), but the underlying mechanisms remain unclear. This study was designed to test the hypothesis that concurrent early atherosclerosis and hypoperfusion might have greater early deleterious effects on the function and structure of the stenotic kidney. Methods and Results-Regional renal hemodynamics and function at baseline and during vasoactive challenge (acetylcholine or sodium nitroprusside) were quantified in vivo in pigs by electron-beam computed tomography after a 12-week normal (nϭ7) or hypercholesterolemic (HC, nϭ7) diet, RAS (nϭ6), or concurrent HC and a similar degree of RAS (HCϩRAS, nϭ7). Flash-frozen renal tissue was studied ex vivo. Basal cortical perfusion and single-kidney glomerular filtration rate (GFR) were decreased similarly in the stenotic RAS and HCϩRAS kidneys, but tubular fluid reabsorption was markedly impaired only in HCϩRAS. Perfusion responses to challenge were similarly blunted in the experimental groups. Stimulated GFR increased in normal, HC, and RAS (38.3Ϯ3.6%, 36.4Ϯ7.6%, and 60.4Ϯ9.3%, respectively, PϽ0.05), but not in HCϩRAS (6.5Ϯ15.1%). These functional abnormalities in HCϩRAS were accompanied by augmented perivascular, tubulointerstitial, and glomerular fibrosclerosis, inflammation, systemic and tissue oxidative stress, and tubular expression of nuclear factor-B and inducible nitric oxide synthase. Conclusions-Early chronic HCϩRAS imposes distinct detrimental effects on renal function and structure in vivo and in vitro, evident primarily in the tubular and glomerular compartments. Increased oxidative stress may be involved in the proinflammatory and progrowth changes observed in the stenotic HCϩRAS kidney, which might potentially facilitate the clinically observed progression to end-stage renal disease.

Abstract-Nitric oxide (NO) mediates multiple physiological and pathophysiological processes in the cardiovascular system. Pharmacological compounds that release NO have been useful tools for evaluating the pivotal role of NO in cardiovascular physiology and therapeutics. These agents constitute two broad classes of compounds, those that release NO or one of its redox congeners spontaneously and those that require enzymatic metabolism to generate NO. In addition, several commonly used cardiovascular drugs exert their beneficial action, in part, by modulating the NO pathway. Here, we review these classes of agents, summarizing their fundamental chemistry and pharmacology, and provide an overview of their cardiovascular mechanisms of action. ysfunction of the normally protective endothelium is found in several cardiovascular diseases, including atherosclerosis, hypertension, heart failure, coronary heart disease, arterial thrombotic disorders, and stroke. [1][2][3][4][5][6] Endothelial dysfunction leads to nitric oxide (NO) deficiency, 1,6 -11 which has been implicated in the underlying pathobiology of many of these disorders (NO insufficiency states). (For a detailed overview of the role of NO in cardiovascular biology and pathobiology, the reader is referred to Loscalzo and Vita. 3 ) NO insufficiency may reflect an absolute deficit of NO (synthesis), impaired availability of bioactive NO, or enhanced NO inactivation. Whatever its biochemical basis, NO insufficiency limits NO-mediated signal transduction of normal or protective physiological processes. In light of this pathobiology, replacement or augmentation of endogenous NO by exogenously administered NO donors has provided the foundation for a broad field of pharmacotherapeutics in cardiovascular medicine.Organic nitrate and nitrite esters represent a time-honored class of NO-donating agents used in cardiovascular therapeutics since the 19th century. These agents have direct vasoactive effects that have been used to treat ischemic heart disease, heart failure, and hypertension for many years. Treatment with conventional nitrate preparations is limited by their therapeutic half-life, systemic absorption with potentially adverse hemodynamic effects, and drug tolerance. 1,6 To overcome these limitations, novel NO donors that offer selective effects, a prolonged half-life, and a reduced incidence of drug tolerance have been developed. NO donors are pharmacologically active substances that spontaneously release, or are metabolized to, NO or its redox congeners. In the present article, we review our current understanding of NO-donating compounds and of cardiovascular drugs that modulate the bioactivity of endogenously produced NO. NO DonorsBecause of the limited utility of authentic NO gas in many experimental systems and the short half-life of NO in vivo, compounds that have the capacity to release NO have been widely used as therapeutic agents and as pharmacological tools to investigate the role of NO in cardiovascular physiology and pathophysiology. Several NO do...

The serine-threonine kinase Akt seems to be central in mediating stimuli from different classes of receptors. In fact, both IGF-1 and IL6-like cytokines induce hypertrophic and antiapoptotic signals in cardiomyocytes through PI3K-dependent Akt activation. More recently, it was shown that Akt is involved also in the hypertrophic and antiapoptotic effects of ␤-adrenergic stimulation. Thus, to determine the effects of Akt on cardiac function in vivo, we generated a model of cardiac-specific Akt overexpression in mice. Transgenic mice were generated by using the E40K, constitutively active mutant of Akt linked to the rat ␣-myosin heavy chain promoter. The effects of cardiac-selective Akt overexpression were studied by echocardiography, cardiac catheterization, histological and biochemical techniques. We found that Akt overexpression produced cardiac hypertrophy at the molecular and histological levels, with a significant increase in cardiomyocyte cell size and concentric LV hypertrophy. Akt-transgenic mice also showed a remarkable increase in cardiac contractility compared with wildtype controls as demonstrated by the analysis of left ventricular (dP͞dt max) in an invasive hemodynamic study, although with graded dobutamine infusion, the maximum response was not different from that in controls. Diastolic function, evaluated by left ventricular dP͞dt min, was not affected at rest but was impaired during graded dobutamine infusion. Isoproterenol-induced cAMP levels, ␤-adrenergic receptor (␤-AR) density, and ␤-AR affinity were not altered compared with control mice. Moreover, studies on signaling pathway activation from myocardial extracts demonstrated that glycogen synthase kinase3-␤ is phosphorylated, whereas p42͞44 mitogen-activated protein kinases is not, indicating that Akt induces hypertrophy in vivo by activating the glycogen synthase kinase3-␤͞GATA 4 pathway. In summary, our results not only demonstrate that Akt regulates cardiomyocyte cell size in vivo, but, importantly, show that Akt modulates cardiac contractility in vivo without directly affecting ␤-AR signaling capacity.

Several experimental and clinical studies have shown that oxidized low-density lipoprotein and oxidation-sensitive mechanisms are central in the pathogenesis of vascular dysfunction and atherogenesis. Here, we have used p66 Shc؊/؊ and WT mice to investigate the effects of high-fat diet on both systemic and tissue oxidative stress and the development of early vascular lesions. To date, the p66 Shc؊/؊ mouse is the unique genetic model of increased resistance to oxidative stress and prolonged life span in mammals. Computer-assisted image analysis revealed that chronic 21% highfat treatment increased the aortic cumulative early lesion area by Ϸ21% in WT mice and only by 3% in p66 Shc؊/؊ mice. Early lesions from p66 Shc؊/؊ mice had less content of macrophage-derived foam cells and apoptotic vascular cells, in comparison to the WT. Furthermore, in p66 Shc؊/؊ mice, but not WT mice, we found a significant reduction of systemic and tissue oxidative stress (assessed by isoprostanes, plasma low-density lipoprotein oxidizability, and the formation of arterial oxidation-specific epitopes). These results support the concept that p66 Shc؊/؊ may play a pivotal role in controlling systemic oxidative stress and vascular diseases. Therefore, p66 Shc might represent a molecular target for therapies against vascular diseases.atherosclerosis ͉ oxygen radicals ͉ transgenic mouse T he p66Shc protein is one of the three isoforms encoded by the mammalian Shc locus. The Shc overlapping proteins (p66 Shc , p52 Shc , and p46 Shc ) share a C-terminal Src homology 2 (SH2) domain, a central collagen-homologous (CH) region, and an N-terminal phosphotyrosine binding domain and differ for N termini of different lengths. P66 Shc , in particular, is characterized by an additional CH region at the N terminus. Shc proteins are cytoplasmic substrates of activated tyrosine kinases and have been implicated in the transmission of activation signals from tyrosine kinases to Ras proteins (1-3). In 1999, it became clear that Shc proteins might serve broad cellular functions. Homozygous mutation of p66Shc in mice was shown to induce increased resistance to oxidative stress and lifespan extension (4). Recently, it has been demonstrated that the p66 Shc longevity gene increases intracellular reactive oxygen species (ROS), thereby affecting the rate of oxidative damage to nucleic acids; in advance p66 Shc function on ROS, metabolism is necessary for appropriate p53-dependent apoptosis (5).Cells within the arterial wall produce several species of free radicals, and, as is well known, an important functional index of healthy status is represented by vascular function (reviewed in refs. 6 and 7). A multitude of clinical studies and reports with experimental animal models have shown that oxidized lowdensity lipoprotein (oxLDL) and redox-sensitive pathways are key modulators of vascular dysfunction and atherogenesis (reviewed in refs. 8-10). Interestingly, oxLDL and its byproducts may induce early proatherogenic events not only in adults but also in arteries of the ...