Uric acid level is positively associated with NT-proBNP concentration in Slovak heart failure patients.

Increased concentration of uric acid (UA) is positively associated with the clinical severity but negatively associated with the prognosis of heart failure (HF). However, data related to the association between UA concentration and N-terminal pro brain natriuretic peptide (NT-proBNP) are still lacking. The aim of the study was to analyze the relationships between UA, NT-proBNP, clearance of creatinine and NYHA function class and echocardiographic variables in the Slovak population of primary care patients diagnosed with HF. The association between UA and NT-proBNP was assessed by multivariate analysis. 848 patients (402 men, 446 women) with HF were included in the study. NT-proBNP correlated with UA in both men and women after adjustment based on age, BMI and glomerular filtration rate (r=0.263, p<0.0001; r=0.293, p<0.0001). UA concentration rose with the severity of the NYHA class and was significantly higher in patients with moderate and severe systolic dysfunctions as well as with diastolic dysfunction in the multivariate analysis. In conclusion, our study in Slovak population with HF has revealed a positive correlation between the concentration of UA and NT-proBNP, and the independency of this association on confounding factors. The results support the role of UA as a biochemical marker of HF severity and prognosis.

Relations between markers of cardiac remodelling and left ventricular collagen in an isoproterenol-induced heart damage model.

There is a great urgency of detecting and monitoring myocardial fibrosis in clinical practice with the aim to improve and personalize therapy against cardiac remodelling. Hence, the aim of this study was to describe alterations in and show potential correlations between the structural characteristics and the molecular and biochemical markers of cardiac remodelling on a model of isoproterenol-induced heart failure. Two groups of 3-month-old male Wistar rats (n = 8 per group) were sacrificed after four weeks of treatment: control (placebo), ISO (5 mg/kg/day intraperitoneally). Chronic ISO treatment led to heart failure (HF) characterized by significant reduction of systolic blood pressure (SBP) accompanied by an increase in left ventricular weight (LVW) along with increased collagen content in the LV. The collagen content correlated negatively with SBP (R = -0.776, P < 0.001) and positively with LVW (R = 0.796, P < 0.001), with Col1a1 (0.83; P < 0.001) and Acta2 (0.73; P < 0.01). Moreover, the mRNA expression of fibrotic remodelling indicator, i.e. TGF-ß1 tended to increase, while the level of fibrinolysis markers (MCP-1, TIMP-2, MMP) were unchanged. The plasma markers of collagen, procollagen I C-terminal propeptide (PICP) was 37.34 ± 7.10 pg/mL in control and was reduced by 42% (P < 0.05) in the ISO group and procollagen III N-terminal propeptide (PIIINP) was 1216.7 ± 191.0 pg/mL in control and was decreased by 66% (P < 0.05) in the ISO group. Surprisingly, there was no positive correlation between plasma markers of collagen, i.e. PICP and PIIINP and collagen content or molecular markers of collagen. However, both PICP and PIIINP correlated with BW (R = 0.712, resp. 0.803, P < 0.001), which was significantly reduced (by 25%, P < 0.05) in the ISO group. In conclusion, we assume that the collagen content of the left ventricle does not need unavoidably correlate with plasma markers of collagen, which might be affected by confounding factors in heart failure, such as loss of body weight, presumably associated with a catabolic condition.

Ivabradine does not impair anxiety-like behavior and memory in both healthy and L-NAME-induced hypertensive rats.

Cardiovascular pathologies are frequently associated with anxiety and other behavioral disturbances. Ivabradine, an inhibitor of the hyperpolarization-activated cyclic nucleotide-gated channels in the sinoatrial node, decreases heart rate and provides cardiovascular protection. Although ivabradine is increasingly used in cardiovascular medicine, the data on its behavioral effects are lacking. The aim of this work was to show ivabradine's potential effect on behavior in healthy and hypertensive rats. After a four-week treatment period, systolic blood pressure was increased in the N(G)-nitro-L-arginine methyl ester (L-NAME)-group and ivabradine significantly reduced it. Furthermore, it reduced the heart rate in both the control and L-NAME-group. In the control group, ivabradine enhanced the time spent in and transition to the open arms of the elevated plus maze test (EPM). In the L-NAME-group, ivabradine does not show a significant effect on the time spent in the EPM open arms and the number of transitions into them. Furthermore, ivabradine has no impact on cognitive function in both control and L-NAME groups. We conclude that ivabradine showed no undesirable effects on anxiety, locomotion or learning; in fact, some of these parameters were even improved. For the first time it has been shown that ivabradine is a safe cardiovascular drug regarding its effect on psycho-behavioral manifestations.

Effect of ivabradine, captopril and melatonin on the behaviour of rats in L-nitro-arginine methyl ester-induced hypertension.

Cardiovascular diseases including hypertension are often associated with behavioural alterations. The aim of this study was to show, whether ivabradine, the blocker of If-channel in sinoatrial node, is able to modify the behaviour of rats in L-nitro-arginine methyl ester (L-NAME)-induced hypertension and to compare the effect of ivabradine with captopril and melatonin. 12-week-old male Wistar rats were divided into the following groups: controls, ivabradine (10 mg/kg/24 h), L-NAME (40 mg/kg/24 h), L-NAME + ivabradine, L-NAME + captopril (100 mg/kg/24 h), L-NAME + melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP) and heart rate (HR) were measured by tail-cuff method once a week. The behaviour of rats was investigated during 23-hours in the phenotyper after four weeks of the treatment. Chronic administration of L-NAME induced hypertension without a change in HR. All tested substances partly prevented the increase of SBP, while ivabradine and melatonin also reduced HR. Ivabradine, captopril and melatonin reduced daily food intake, slightly decreased daily water intake and attenuated body weight gain. In L-NAME group, locomotor activity was enhanced by ivabradine, whereas exploratory behaviour was increased by melatonin and captopril. In conclusion, ivabradine, besides its potentially protective hemodynamic actions, does not seem to exert any disturbing effects on behaviour in L-NAME-induced hypertension in rats, while some of its effects were similar to captopril or melatonin. It is suggested that ivabradine used in cardiovascular indications is harmless regarding the effect on behaviour.

[Epidemiologic data of hyperuricaemia prevalence in the conditions of primary care in Slovakia]. / Epidemiologické údaje o výskyte hyperurikémie u muzov a u zien v podmienkach primárnej liecebnej starostlivosti na Slovensku.

Hyperuricaemia represents nowaday the new risk factor for cardiovascular diseases. Prevalence data and its treatment in our patient's population are still missing. Literature data shows, that its prevalence differs in various populations significantly from 4% up to 40% with race and geographical means. In the hospital population its prevalence is about 7% and represents the important predictor of hospital mortality, e.i with heart failure. From the Framingham data relative risk was estimated of 25% for cardiovascular diseases, coronary heart disease and all-course mortality. From the epidemiologic survey Mirror Slovakia hyperuricaemia was evaluated from the sample of 20 000 patients from the primare care physicians in order to see the picture on this newer risk factor.

[Epidemiologic data of hyperuricaemia prevalence in the conditions of primary care in Slovakia]. / Epidemiologické údaje o výskyte hyperurikémie u muzov a u zien v podmienkach primárnej liecebnej starostlivosti na Slovensku.

UNLABELLED: Hyperuricaemia represents nowaday the new risk factor for cardiovascular diseases. Prevalence data and its treatment in our patient´s population are still missing. Literature data shows, that its prevalence differs in various populations significantly from 4 % up to 40 % with race and geographical means. In the hospital population its prevalence is about 7 % and represents the important predictor of hospital mortality, e.i with heart failure. From the Framingham data relative risk was estimated of 25 % for cardiovascular diseases, coronary heart disease and all-course mortality. From the epidemiologic survey Mirror Slovakia hyperuricaemia was evaluated from the sample of 20 000 patients from the primare care physicians in order to see the picture on this newer risk factor. KEY WORDS: cardiovascular diseases - epidemiology - hyperuricaemia - therapy.

Doxorubicin-induced behavioral disturbances in rats: protective effect of melatonin and captopril.

OBJECTIVE: Doxorubicin is a recognized chemotherapeutic agent widely employed in human malignancies. The limiting factor of its use is a number of side effects. The aim of this work was to show, whether administration of doxorubicin could induce behavioral disturbances in rats, and whether angiotensin-converting enzyme inhibitor captopril or melatonin can modify these potential alterations. DESIGN AND METHODS: Four groups of 3-month-old Wistar rats (twelve per group) were treated for 4 weeks: control (placebo-treated), doxorubicin (DOX) (5mg/kg i.v. in a single intravenous dose), DOX rats treated with either melatonin (10mg/kg/24h) or captopril (100mg/kg/24h). Systolic blood pressure (SBP) and the level of oxidative stress were investigated and behavioral tests of anxiety-open field test (OF), elevated plus maze (EPM) and light-dark box (LDB) were accomplished. RESULTS: Doxorubicin increased significantly systolic blood pressure and parameters of oxidative stress. Moreover, doxorubicin enhanced the level of anxiety in the tests of OF, EPM, and LDB. Captopril and melatonin prevented the blood pressure rise and the enhancement of oxidative load. Importantly, both substances reduced the parameters of anxiety. CONCLUSION: Chronic administration of captopril or melatonin has shown anxiolytic effect in the model of doxorubicin-induced anxiety. It does not seem unreasonable to suppose that this protective effect of captopril or melatonin against anxiety development might have been related to the antioxidative effects of both substances.

Effect of captopril and melatonin on fibrotic rebuilding of the aorta in 24 hour light-induced hypertension.

Chronic continuous light exposure leads to melatonin deficiency along with complex neurohumoral activation resulting in hypertension development in rats. The aim of this study was to show, whether continuous light induces fibrotic rebuilding of the aorta and whether the treatment with melatonin or angiotensin converting enzyme inhibitor captopril can prevent these potential alterations. In a six-week experiment, 3-month-old Wistar rats were divided into 4 groups (ten per group): controls, rats exposed to continuous light, exposed to continuous light plus treated with captopril (100 mg/kg/24 h) and exposed to continuous light plus treated with melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP) and collagen type I and III in the media of thoracic aorta were measured. Continuous light induced hypertension and fibrotic rebuilding of the aorta in terms of enhancement of collagen I and III concentration in the aortic media. Both captopril and melatonin prevented SBP rise and reduced collagen III concentration in the aorta. However, only melatonin reduced collagen I and the sum of collagen I and III in the aortic tissue. We conclude that in continuous light-induced hypertension, administration of melatonin, along with SBP reduction, decreases collagen I and III concentration in the aorta. It is suggested that antifibrotic effect of melatonin may reduce the stiffness of the aorta and small arteries and beneficially influence the nature of the pulse wave and peripheral vascular resistance.

Protective effect of captopril, olmesartan, melatonin and compound 21 on doxorubicin-induced nephrotoxicity in rats.

Chronic kidney disease (CKD) represents a serious public health problem with increasing prevalence and novel approaches to renal protection are continuously under investigation. The aim of this study was to compare the effect of melatonin and angiotensin II type 2 receptor agonist compound 21 (C21) to angiotensin converting enzyme inhibitor captopril and angiotensin II type 1 receptor blocker olmesartan on animal model of doxorubicin nephrotoxicity. Six groups of 3-month-old male Wistar rats (12 per group) were treated for four weeks. The first group served as a control. The remaining groups were injected with a single dose of doxorubicin (5 mg/kg i.v.) at the same day as administration of either vehicle or captopril (100 mg/kg/day) or olmesartan (10 mg/kg/day) or melatonin (10 mg/kg/day) or C21 (0.3 mg/kg/day) was initiated. After four week treatment, the blood pressure and the level of oxidative stress were enhanced along with reduced glomerular density and increased glomerular size. Captopril, olmesartan and melatonin prevented the doxorubicin-induced increase in systolic blood pressure. All four substances significantly diminished the level of oxidative burden and prevented the reduction of glomerular density and modestly prevented the increase of glomerular size. We conclude that captopril, olmesartan, melatonin and C21 exerted a similar level of renoprotective effects in doxorubicin-induced nephrotoxicity.

Multiplexed immunoassays for simultaneous quantification of cardiovascular biomarkers in the model of H(G)-nitro-L-arginine methylester (L-NAME) hypertensive rat.

The multimarker approach using Luminex technology represents a new tool for studying the pathogenesis of cardiovascular disease. Although many cardiac biomarkers in heart failure have been well established, the role and significance of their measurement in hypertensive patients is still questionable. The aim of our study was to evaluate the relationship of selected biomarkers in L-NAME-induced hypertension to the left ventricular remodeling in the two different periods of hypertension development. Four groups of 3-month-old male Wistar rats were investigated: (1) control 4 (placebo for 4 weeks), (2) control 7 (placebo for 7 weeks), (3) L-NAME 4 (40 mg/kg/day for 4 weeks), and (4) L-NAME 7 (40 mg/kg/day for 7 weeks). BNP, cTnI, TNF-α, and VEGF were measured using Rat CVD Panel 1 Kit (Milliplex® MAP). Cardiac troponin T was determined using Elecsys® Troponin T high sensitive immunoassay (Roche, Switzerland). Although the systolic blood pressure increases about 50% in L-NAME-induced hypertension in rat, both hypertrophy and fibrosis were expressed only slightly in this experiment. The levels of BNP, TNF-α, or VEGF did not differ significantly among groups. However, cardiac troponin T measured by high sensitive ELISA was significantly (P<0.05) increased in L-NAME 4 (0.229 µg/l versus 0.034 µg/l) and L-NAME-7 groups (0.366 µg/l versus 0.06 µg/l) in comparison with the controls. We conclude that the slightly increased cTnT levels could indicate ischemic damage of L-NAME-hypertensive heart. Importantly, to our best knowledge, this is the first study indicating that CVD rat panel may be a useful methodological tool in experimental cardiology.

Multi-nuclear magnetic resonance study of Na3AlF6-AlPO4 molten and solidified mixtures.

Phosphorus is one of the predominant impurities in the Hall-Heroult process for industrial aluminium production. The nature of the dissolved phosphorus species in the Na(3)AlF(6)-AlPO(4) system has been investigated by in situ high-temperature (HT) (19)F, (23)Na, (27)Al, (17)O, and (31)P NMR. The combination of these experiments enables to define the presence of PO(4)(3-), AlF(5)(2-) and (AlF(4)-O-PO(3))(4-) anions in the melt, and then the formation of Al-O-P bonding. Melts solidified at different cooling rates were characterised using various solid-state NMR techniques including multiple quantum magic angle spinning (MQMAS), rotational echo double resonance (REDOR) and heteronuclear single quantum correlation (HSQC). The glass obtained by the rapid quenching of the hypereutectic melt has been carefully described in order to better understand the structure of the melt.

Regression of left ventricular hypertrophy and aortic remodelling in NO-deficient hypertensive rats: effect of L-arginine and spironolactone.

AIM: We investigated, whether the substrate for nitric oxide (NO) formation -L-arginine - and the aldosterone receptor antagonist - spironolactone - are able to reverse alterations of the left ventricle (LV) and aorta in N(omega)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. METHODS: Six groups of male adult Wistar rats were investigated: controls after 4 and 7 weeks of experiment, rats treated with L-NAME for 4 weeks and three recovery groups: spontaneous-reversion (4 weeks L-NAME + 3 weeks placebo), spironolactone-induced reversion (4 weeks L-NAME + 3 weeks spironolactone) and L-arginine-induced reversion (4 weeks L-NAME+ 3 weeks L-arginine). Blood pressure was measured by tail-cuff plethysmography. Relative weight of the LV, myocardial fibrosis (based upon histomorphometry and hydroxyproline determination) and conjugated dienes in the LV and aortic cross-sectional area, inner diameter and wall thickness were determined. NO-synthase activity was investigated in the LV and aorta. RESULTS: L-NAME administration induced hypertension, left ventricular hypertrophy (LVH), LV fibrosis, aortic thickening and diminution of NO-synthase activity in the LV and aorta. Reduction in blood pressure and regression of LVH were observed in all recovery groups, yet reduction in LV fibrosis and aortic thickening were not. NO-synthase activity was restored only in the L-arginine and spironolactone group. CONCLUSION: In our study, the reversion of hypertension and LVH was not dependent on the restoration of NO-synthase activity. Moreover, LV fibrosis and aortic remodelling seem to be more resistant to conditions resulting in regression of LVH. Preserved level of fibrosis in the initial period of LVH regression might result in loss of structural homogeneity and possible functional alterations of the LV.

Morphological alterations and NO-synthase expression in the heart after continuous light exposure of rats.

Although exposure to continuous light is associated with hypertension and modulates the outcome of ischemia-reperfusion injury, less attention has been paid to its effects on cardiac morphology. We investigated whether 4-week exposure of experimental rats to continuous 24 h/day light can modify cardiac morphology, with focus on heart weight, fibrosis and collagen I/III ratio in correlation with NO-synthase expression. Two groups of male adult Wistar rats were studied: controls exposed to normal light/dark cycle (12 h/day light, 12 h/day dark) and rats exposed to continuous light. After 4 weeks of treatment the absolute and the relative heart weights were determined and myocardial fibrosis and collagen type I/III ratio were evaluated using picrosirius red staining. Endothelial and inducible NO-synthase expression was detected immunohistochemically. The exposure of rats to continuous light resulted in an increase of body weight with proportionally increased heart weight. Myocardial fibrosis remained unaffected but collagen I/III ratio increased. Neither endothelial nor inducible NO-synthase expression was altered in light-exposed rats. We conclude that the loss of structural homogeneity of the myocardium in favor of collagen type I might increase myocardial stiffness and contribute to functional alterations after continuous light exposure.

The effect of continuous light exposure of rats on cardiac response to ischemia-reperfusion and NO-synthase activity.

Factors modulating cardiac susceptibility to ischemia-reperfusion (I/R) are permanently attracting the attention of experimental cardiology research. We investigated, whether continuous 24 h/day light exposure of rats can modify cardiac response to I/R, NO-synthase (NOS) activity and the level of oxidative load represented by conjugated dienes (CD) concentration. Two groups of male adult Wistar rats were studied: controls exposed to normal light/dark cycle (12 h/day light, 12 h/day dark) and rats exposed to continuous light for 4 weeks. Perfused isolated hearts (Langendorff technique) were exposed to 25 min global ischemia and subsequent 30 min reperfusion. The recovery of functional parameters (coronary flow, left ventricular developed pressure, contractility and relaxation index) during reperfusion as well as the incidence, severity and duration of arrhythmias during first 10 min of reperfusion were determined. The hearts from rats exposed to continuous light showed more rapid recovery of functional parameters but higher incidence, duration and severity of reperfusion arrhythmias compared to controls. In the left ventricle, the NOS activity was attenuated, but the CD concentration was not significantly changed. We conclude that the exposure of rats to continuous light modified cardiac response to I/R. This effect could be at least partially mediated by attenuated NO production.

Spontaneous, L-arginine-induced and spironolactone-induced regression of protein remodeling of the left ventricle in L-NAME-induced hypertension.

N(G)-nitro-L-arginine-methyl ester (L-NAME)-induced hypertension is associated with protein remodeling of the left ventricle. The aim of the study was to show, whether aldosterone receptor blocker spironolactone and precursor of NO-production L-arginine were able to reverse the protein rebuilding of the left ventricle. Six groups of male Wistar rats were investigated: control 4 (4 weeks placebo), L-NAME (4 weeks L-NAME), spontaneous-regression (4 weeks L-NAME + 3 weeks placebo), spironolactone-regression (4 weeks L-NAME + 3 weeks spironolactone), L-arginine-regression (4 weeks L-NAME + 3 weeks arginine), control 7 (7 weeks placebo). L-NAME administration induced hypertension, hypertrophy of the left ventricle (LV), and the increase of metabolic and contractile as well as soluble and insoluble collagenous protein concentration. The systolic blood pressure and relative weight of the LV decreased in all three groups with regression, while the most prominent attenuation of the LVH was observed after spironolactone treatment. In the spontaneous-regression and L-arginine-regression groups the concentrations of individual proteins were not significantly different from the control value. However, in the spironolactone-regression group the concentration of metabolic, contractile and insoluble collagenous proteins remained significantly increased in comparison with the control group. The persistence of the increased protein concentration in the spironolactone group may be related to the more prominent reduction of myocardial water content by spironolactone.

Simvastatin decreased coenzyme Q in the left ventricle and skeletal muscle but not in the brain and liver in L-NAME-induced hypertension.

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (statins) have been proven to reduce effectively cholesterol level and morbidity and mortality in patients with coronary heart disease and/or dyslipoproteinemia. Statins inhibit synthesis of mevalonate, a precursor of both cholesterol and coenzyme Q (CoQ). Inhibited biosynthesis of CoQ may be involved in some undesirable actions of statins. We investigated the effect of simvastatin on tissue CoQ concentrations in the rat model of NO-deficient hypertension induced by chronic L-NAME administration. Male Wistar rats were treated daily for 6 weeks with L-NAME (40 mg/kg) or with simvastatin (10 mg/kg), another group received simultaneously L-NAME and simvastatin in the same doses. Coenzyme Q(9) and Q(10) concentrations were analyzed by high performance liquid chromatography. L-NAME and simvastatin alone had no effect on CoQ concentrations. However, simultaneous application of L-NAME and simvastatin significantly decreased concentrations of both CoQ homologues in the left ventricle and slightly decreased CoQ(9) concentration in the skeletal muscle. No effect was observed on CoQ level in the liver and brain. We conclude that the administration of simvastatin under the condition of NO-deficiency reduced the level of CoQ in the heart and skeletal muscle what may participate in adverse effect of statins under certain clinical conditions.

Comparison of the effect of simvastatin, spironolactone and L-arginine on endothelial function of aorta in hereditary hypertriglyceridemic rats.

Hereditary hypertriglyceridemic (hHTG) rats are characterized by increased blood pressure and impaired endothelium-dependent relaxation of conduit arteries. The aim of this study was to investigate the effect of long-term (4 weeks) treatment of hHTG rats with three drugs which, according to their mechanism of action, may be able to modify the endothelial function: simvastatin (an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase), spironolactone (an antagonist of aldosterone receptors) and L-arginine (a precursor of nitric oxide formation). At the end of fourth week the systolic blood pressure in the control hHTG group was 148+/-2 mm Hg and in control normotensive Wistar group 117+/-3 mm Hg. L-arginine failed to reduce blood pressure, but simvastatin (118+/-1 mm Hg) and spironolactone (124+/-4 mm Hg) treatment significantly decreased the systolic blood pressure. In isolated phenylephrine-precontracted aortic rings from hHTG rats endothelium-dependent relaxation was diminished as compared to control Wistar rats. Of the three drugs used, only simvastatin improved acetylcholine-induced relaxation of the aorta. We conclude that both simvastatin and spironolactone reduced blood pressure but only simvastatin significantly improved endothelial dysfunction of aorta. Prominent increase in the expression of eNOS in large conduit arteries may be the pathophysiological mechanism underlying the protective effect of simvastatin in hHTG rats.

Spironolactone differently influences remodeling of the left ventricle and aorta in L-NAME-induced hypertension.

Aldosterone receptor antagonist, spironolactone, has been shown to prevent remodeling of the heart in several models of left ventricular hypertrophy. The aim of the present study was to determine whether the treatment with spironolactone can prevent hypertension, reduction of tissue nitric oxide synthase activity and left ventricular (LV) and aortic remodeling in N(G)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Four groups of rats were investigated: control, spironolactone (200 mg/kg), L-NAME (40 mg/kg) and L-NAME + spironolactone (in corresponding dosage). Animals were studied after 5 weeks of treatment. The decrease of NO-synthase activity in the LV and kidney was associated with the development of hypertension and LV hypertrophy, with increased DNA concentration in the LV, and remodeling of the aorta in the L-NAME group. Spironolactone prevented the inhibition of NO-synthase activity in the LV and kidney and partially attenuated hypertension and LVH development and the increase in DNA concentration. However, remodeling of the aorta was not prevented by spironolactone treatment. We conclude that the aldosterone receptor antagonist spironolactone improved nitric oxide production and partially prevented hypertension and LVH development without preventing hypertrophy of the aorta in NO-deficient hypertension. The reactive growth of the heart and aorta seems to be controlled by different mechanisms in L-NAME-induced hypertension.

The role of nitric oxide in the maintenance of vasoactive balance.

Endothelial dysfunction may be considered as the interstage between risk factors and cardiovascular pathology. An imbalance between the production of vasorelaxing and vasoconstricting factors plays a decisive role in the development of hypertension, atherosclerosis and target organ damage. Except vasorelaxing and antiproliferative properties per se, nitric oxide participates in antagonizing vasoconstrictive and growth promoting effects of angiotensin II, endothelins and reactive oxygen species. Angiotensin II is a potent activator of NAD(P)H oxidase contributing to the production of reactive oxygen species. Numerous signaling pathways activated in response to angiotensin II and endothelin-1 are mediated through the increased level of oxidative stress, which seems to be in casual relation to a number of cardiovascular disturbances including hypertension. With respect to the oxidative stress, the NO molecule seems to be of ambivalent nature. On the one hand, NO is able to reduce generation of reactive oxygen species by inhibiting association of NAD(P)H oxidase subunits. On the other hand, when excessively produced, NO reacts with superoxides resulting in the formation of peroxynitrite, which is a free radical deteriorating endothelial function. The balance between vasorelaxing and vasoconstricting substances appears to be the principal issue for the physiological functioning of the vascular bed.

Is NO the king? Pathophysiological benefit with uncertain clinical impact.

NO is the "hero" molecule of the last few decades. It is a ubiquitous and omnipotent radical with both hemodynamic and antiproliferative effects within the cardiovascular system. NO is an important counterregulatory factor for vasoconstrictors and growth promoting substances. Endothelial dysfunction with decreased NO production is related to many cardiovascular disorders, such as coronary artery disease, heart failure and hypertension. Despite the important role of NO within the circulation, there is only limited evidence in the form of large clinical trials that NO delivery can reduce cardiovascular morbidity and mortality. Thus, NO donors are not in the first line therapy in ischemic heart disease, heart failure or arterial hypertension and NO delivery is recommended only in particular clinical situations, when a well established treatment is contraindicated or has an insufficient effect. It is concluded that the insufficient NO production is the principal disorder in endothelial dysfunction, which is related to cardiovascular pathology with deteriorated prognosis, but the impact of therapeutically increased NO bioactivity on the morbidity and mortality is inferior to well established treatment with ACE-inhibitors, AT(1) receptor blockers, beta-blockers, statins and certain antihypertensive drugs. There is little doubt that NO is king in the circulation, but kings seldom decide the battles.