Restoration of Vitamin D Levels Improves Endothelial Function and Increases TASK-Like K+ Currents in Pulmonary Arterial Hypertension Associated with Vitamin D Deficiency.

Background: Vitamin D (vitD) deficiency is highly prevalent in patients with pulmonary arterial hypertension (PAH). Moreover, PAH-patients with lower levels of vitD have worse prognosis. We hypothesize that recovering optimal levels of vitD in an animal model of PAH previously depleted of vitD improves the hemodynamics, the endothelial dysfunction and the ionic remodeling. Methods: Male Wistar rats were fed a vitD-free diet for five weeks and then received a single dose of Su5416 (20 mg/Kg) and were exposed to vitD-free diet and chronic hypoxia (10% O2) for three weeks to induce PAH. Following this, vitD deficient rats with PAH were housed in room air and randomly divided into two groups: (a) continued on vitD-free diet or (b) received an oral dose of 100,000 IU/Kg of vitD plus standard diet for three weeks. Hemodynamics, pulmonary vascular remodeling, pulmonary arterial contractility, and K+ currents were analyzed. Results: Recovering optimal levels of vitD improved endothelial function, measured by an increase in the endothelium-dependent vasodilator response to acetylcholine. It also increased the activity of TASK-1 potassium channels. However, vitD supplementation did not reduce pulmonary pressure and did not ameliorate pulmonary vascular remodeling and right ventricle hypertrophy. Conclusions: Altogether, these data suggest that in animals with PAH and severe deficit of vitD, restoring vitD levels to an optimal range partially improves some pathophysiological features of PAH.

Probiotics Prevent Dysbiosis and the Rise in Blood Pressure in Genetic Hypertension: Role of Short-Chain Fatty Acids.

SCOPE: The objective of this study is to determine the cardiovascular effects of the probiotics Bifidobacterium breve CECT7263 (BFM) and Lactobacillus fermentum CECT5716 (LC40), and the short chain fatty acids butyrate, and acetate in spontaneously hypertensive rats (SHR). METHODS AND RESULTS: Ten five-week old Wistar Kyoto rats (WKY) and fifty aged-matched SHR are randomly distributed into six groups: control WKY, control SHR, treated SHR-LC40, treated SHR-BMF, treated SHR-butyrate, and treated SHR-acetate. Chronic treatments with LC40 or BFM increase butyrate-producing bacteria and prevent the blood pressure increase in SHR. Oral treatment with butyrate or acetate also prevents the increase in both blood pressure and Firmicutes/Bacteroidetes (F/B) ratio. All treatments restore the Th17/Treg balance in mesenteric lymph nodes, normalized endotoxemia, and prevent the impairment of endothelium-dependent relaxation to acetylcholine, as a result of reduced NADPH oxidase-driven reactive oxygen species production. These protective effects might be mediated by both the reduction in vascular lipopolysaccharide (LPS)/toll-like receptor 4 (TLR4) pathway and the increase in Treg infiltration in the vasculature. CONCLUSION: The probiotics LC40 and BFM prevent dysbiosis and the development of endothelial dysfunction and high blood pressure in genetic hypertension. These effects seem to be related to endotoxemia reduction and to increase Treg accumulation in the vasculature.

Research trends in flavonoids and health.

Herein we describe, based on some bibliometric data, how the field of research on flavonoids has evolved over the last 25 years. The number of papers on flavonoids has risen in an exponential manner over these years, much faster than other fields on food constituents. This increase appears to be related to the contemporary explosion of interest in healthy foods, supplements and nutraceuticals. It was also probably triggered by large epidemiological studies on fruits and vegetables, and particularly on flavonoids, consumption and incidence of cancer, stroke and coronary heart disease. The widely distributed flavonols constitute the flavonoid subgroup upon which the greatest interest has been focused, followed by flavanols and more recently by anthocyanidins and other related polyphenols such as resveratrol. Research on isoflavones rapidly emerged in the 1990s but plateaued in the 2000s. In the 1990s flavonoids were mainly considered as the active components of medicinal plants, while from 2000 onward, they switched to be mainly regarded as bioactive food ingredients. We envision a continuation in the growth of research for the coming decade focused on clearly demonstrating the importance of flavonoids for human health.

The flavonoid paradox: conjugation and deconjugation as key steps for the biological activity of flavonoids.

Flavonoids have been proposed to exert beneficial effects in the prevention of a large number of diseases, including cancer, cardiovascular disease, and neurodegenerative disorders. Paradoxically, despite the most representative flavonoid--quercetin--exerting biologically demonstrable systemic effects, it is not found in plasma after oral administration and its circulating metabolites show weak activity in vitro. The current available evidence indicates that quercetin is extensively metabolized into methylated and glucurono- and sulfo-conjugated metabolites, which are the plasma circulating forms; and glucurono-, but not sulfo-conjugates, can be hydrolyzed at the vascular level, yielding the parent aglycone which accumulates in tissues. Thus conjugation is a reversible process and, at least regarding the vasodilator and antihypertensive effects, the conjugation-deconjugation cycle appears to be an absolute requirement. Glucuronidated derivatives transport quercetin and its methylated form, and deliver to the tissues the free aglycone, which is the final effector.

Epicatechin: endothelial function and blood pressure.

Epidemiological studies indicate an inverse relationship between flavanol intake and the risk of cardiovascular disease. Potential mechanisms include their effects on endothelial function and hypertension. A number of studies have shown that flavanol-rich cocoa reduces blood pressure and endothelial dysfunction, whereas black tea may have opposite effects. These results highlight the importance of the different effects of the multitude of phytochemical constituents in these foods and the need for studying the individual flavanols. Epicatechin seems to be a major bioactive constituent of cocoa and other flavanol-rich foods and beverages. It has been shown to improve endothelial function in animals and humans. In salt-sensitive animal models of hypertension, epicatechin lowers blood pressure and the associated end-organ damage. Nitric oxide (NO) seems to play a key role in the protection of both hypertension and endothelial dysfunction.

Chronic (-)-epicatechin improves vascular oxidative and inflammatory status but not hypertension in chronic nitric oxide-deficient rats.

The present study analysed the effects of the flavanol (-)-epicatechin in rats after chronic inhibition of NO synthesis with NG-nitro-L-arginine methyl ester (L-NAME), at doses equivalent to those achieved in the studies involving human subjects. Wistar rats were randomly divided into four groups: (1) control-vehicle, (2) L-NAME, (3) L-NAME-epicatechin 2 (L-NAME-Epi 2) and (4) L-NAME-epicatechin 10 (L-NAME-Epi 10). Rats were daily given by oral administration for 4 weeks: vehicle, (-)-epicatechin 2 or 10 mg/kg. Animals in the L-NAME groups daily received L-NAME 75 mg/100 ml in drinking-water. The evolution in systolic blood pressure and heart rate, and morphological and plasma variables, proteinuria, vascular superoxide, reactivity and protein expression at the end of the experiment were analysed. Chronic (-)-epicatechin treatment did not modify the development of hypertension and only weakly affected the endothelial dysfunction induced by L-NAME but prevented the cardiac hypertrophy, the renal parenchyma and vascular lesions and proteinuria, and blunted the prostanoid-mediated enhanced endothelium-dependent vasoconstrictor responses and the cyclo-oxygenase-2 and endothelial NO synthase (eNOS) up-regulation. Furthermore, (-)-epicatechin also increased Akt and eNOS phosphorylation and prevented the L-NAME-induced increase in systemic (plasma malonyldialdehyde and urinary 8-iso-PGF2α) and vascular (dihydroethidium staining, NADPH oxidase activity and p22phox up-regulation) oxidative stress, proinflammatory status (intercellular adhesion molecule-1, IL-1ß and TNFα up-regulation) and extracellular-signal-regulated kinase 1/2 phosphorylation. The present study shows for the first time that chronic oral administration of (-)-epicatechin does not improve hypertension but reduced pro-atherogenic pathways such as oxidative stress and proinflammatory status of the vascular wall induced by blockade of NO production.

Levosimendan increases portal blood flow and attenuates intestinal intramucosal acidosis in experimental septic shock.

It has been proposed that vasodilatory therapy may increase microcirculatory blood flow and improve tissue oxygenation in septic shock. The authors aimed to evaluate the effects of levosimendan in systemic and splanchnic hemodynamics in a porcine model of septic shock in a randomized animal controlled study. This study was performed in an animal research facility in a university hospital. Anesthetized pigs were monitored with a pulmonary artery catheter and an ultrasonic blood flow probe in the portal vein for measurement of systemic and portal blood flows and with a tonometer placed in the small intestine for measurement of the intramucosal-arterial PCO2 gap. Three groups of pigs were studied: nonseptic (n = 7), septic (n = 7), and septic treated with levosimendan (n = 7). Levosimendan was administered i.v. at t = -10 min (200 microg/kg in i.v. bolus followed by 200 microg/kg per h). Sepsis was induced at t = 0 min by the administration of live Escherichia coli. Vascular reactivity was tested by the hemodynamic response to noradrenaline. Levosimendan markedly attenuated the sepsis-induced increase in pulmonary vascular resistance, decrease in portal/systemic blood flow, oliguria, impairment in oxygenation, hyperkalemia, and the widened intramucosal-arterial PCO2 gap. Systemic blood pressure and vascular resistance did not differ as compared with the septic untreated group. Responses to noradrenaline significantly improved in animals treated with levosimendan. Treatment with levosimendan in this animal model of sepsis attenuated pulmonary vasoconstriction and improved portal blood flow, intestinal mucosal oxygenation, pulmonary function, and vascular reactivity.

Glucuronidated metabolites of the flavonoid quercetin do not auto-oxidise, do not generate free radicals and do not decrease nitric oxide bioavailability.

Quercetin, the most abundant flavonoid in the diet, reduces blood pressure and restores endothelial dysfunction in hypertensive animals. However, quercetin (as the aglycone) is usually not present in plasma, but it is rapidly metabolised during absorption by methylation, glucuronidation and sulfation. Depending on the experimental conditions, quercetin can show anti-oxidant or pro-oxidant effects. We have analysed the pro-oxidant effects of quercetin and its methylated (3-methylquercetin or isorhamnetin), sulfated (quercetin 3'-sulfate), glucuronidated (quercetin 3-glucuronide) and methylated plus glucuronidated (isorhamnetin 3-glucuronide) metabolites. Auto-oxidation, O(2)(-) release and NO scavenging were analysed by means of absorption spectra, lucigenin chemiluminescence or superoxide dismutase inhibitable cytochrome C reduction and an amperometric electrode, respectively. The biological activity of NO was tested in rat aortic rings. Quercetin, isorhamnetin and quercetin 3'-sulfate auto-oxidized in aqueous buffer and generated superoxide radical. Quercetin but not the glucuronide scavenged NO. In contrast, the glucuronides were without effect. Quercetin, but not quercetin 3-glucuronide, inhibited the biological activity of NO. These data indicate that, in contrast to quercetin, its main circulating forms, i. e., the glucuronides, do not exert pro-oxidant effects.

Genistein restores caveolin-1 and AT-1 receptor expression and vascular function in large vessels of ovariectomized hypertensive rats.

OBJECTIVE: The soy-derived phytoestrogen genistein improves endothelial function in postmenopausal women and ovariectomized (OVX) normotensive rats. We hypothesized that genistein would improve vascular reactivity involving changes in endothelial nitric oxide synthase (NOS) expression and its regulatory proteins (caveolin and calmodulin), angiotensin II receptor, and/or oxidative status in OVX spontaneously hypertensive rats (SHRs). DESIGN: After ovariectomy or sham operation, 23-week-old female SHRs received either 17beta-estradiol (2 mg/kg/wk SC), genistein (10 mg/kg/d by gavage), or placebo. RESULTS: In OVX rats, final body weight was increased and uterus weight was decreased, and these values were reduced and increased, respectively, by 17beta-estradiol but unaffected by genistein. Acetylcholine-induced endothelium-dependent vasorelaxation was significantly blunted in aortas from OVX placebo SHRs. The contractions induced by the NOS inhibitor L-NAME and angiotensin II in OVX placebo were lower and higher, respectively, than in sham rats. Estradiol and genistein restored these functional changes. Aortic endothelial NOS and calmodulin-1 expression were unchanged, whereas caveolin-1 and angiotensin II receptor expression was increased in OVX rats. Estradiol and genistein treatment did not modify endothelial NOS, but normalized caveolin-1 and angiotensin II receptor and increased calmodulin-1 expression. Vascular superoxide production was increased in OVX placebo and normalized by both estradiol and genistein. CONCLUSIONS: Genistein prevented all cardiovascular changes induced by estrogen depletion in SHRs to a similar extent as estradiol but had no uterotrophic effect. The present findings may help to explain the potential benefits of genistein as a therapeutic agent for preventing menopausal vascular complications, especially in hypertensive women.

Effects of the flavonoid quercetin and its methylated metabolite isorhamnetin in isolated arteries from spontaneously hypertensive rats.

Chronic oral quercetin exerts antihypertensive effects in spontaneously hypertensive rats (SHR). In the present study, the vasodilator effects of the flavonoid quercetin and its main metabolite isorhamnetin were analysed in isolated thoracic aorta, iliac artery and on the isolated perfused mesenteric resistance vascular bed from SHR and normotensive Wistar Kyoto rats (WKY). In noradrenaline-precontracted vessels from SHR there was an inverse correlation between the relaxant potency (pIC50) of quercetin (4.76 +/- 0.02, 5.08 +/- 0.12, 5.30 +/- 0.18, in aorta, iliac arteries and mesentery, respectively) and isorhamnetin (4.90 +/- 0.11, 5.38 +/- 0.15 and 5.80 +/- 0.10, respectively) and the diameter of the vessel studied. Both flavonoids were more potent in endothelium-denuded aortae and iliac arteries from SHR than from normotensive WKY rats. In addition, in aortae from SHR both flavonoids restored the endothelial-dependent vasodilation. Isorhamnetin, but not quercetin, also reduced the endothelium-dependent contractile responses induced by acetylcholine. These direct vasodilator effects, together with the improvement of endothelial function, are good candidates to explain the blood pressure reduction and vascular protective effects of quercetin in animal models of hypertension and possibly in human cardiovascular diseases.

Cardiovascular effects of isorhamnetin and quercetin in isolated rat and porcine vascular smooth muscle and isolated rat atria.

Isorhamnetin and quercetin produced endothelium-independent vasodilator effects in rat aorta, rat mesenteric arteries, rat portal vein and porcine coronary arteries. The effects of the two flavonoids were similar in arteries stimulated by noradrenaline, KCl, U46619 or phorbol esters but the two flavonoids were more potent in the coronary arteries than in the aorta. At high concentrations, they also induced a positive inotropic effect in isolated rat atria. Therefore, at least part of the in vivo effects of quercetin may result from its conversion to isorhamnetin which is the main metabolite of quercetin found in plasma. The arterial, venous and coronary vasodilator effects may contribute to the protective effects of flavonoids in ischaemic heart disease observed in epidemiological studies.