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Chronic oral quercetin reduces blood pressure and restores endothelial dysfunction in hypertensive animals. However, quercetin (aglycone) is usually not present in plasma, because it is rapidly metabolized into conjugated, mostly inactive, metabolites. The aim of the study is to analyze whether deconjugation of these metabolites is involved in the blood pressure lowering effect of quercetin. We have analyzed the effects on blood pressure and vascular function in vitro of the conjugated metabolites of quercetin (quercetin-3-glucuronide, Q3GA; isorhamnetin-3-glucuronide, I3GA; and quercetin-3'-sulfate, Q3'S) in spontaneously hypertensive rats (SHR). Q3GA and I3GA (1 mg/kg i.v.), but not Q3'S, progressively reduced mean blood pressure (MBP), measured in conscious SHR. The hypotensive effect of Q3GA was abolished in SHR treated with the specific inhibitor of β-glucuronidase, saccharic acid 1,4-lactone (SAL, 10 mg/ml). In mesenteric arteries, unlike quercetin, Q3GA had no inhibitory effect in the contractile response to phenylephrine after 30 min of incubation. However, after 1 hour of incubation Q3GA strongly reduced this contractile response and this effect was prevented by SAL. Oral administration of quercetin (10 mg/Kg) induced a progressive decrease in MBP, which was also suppressed by SAL. Conjugated metabolites are involved in the in vivo antihypertensive effect of quercetin, acting as molecules for the plasmatic transport of quercetin to the target tissues. Quercetin released from its glucuronidated metabolites could be responsible for its vasorelaxant and hypotensive effect.

Diabetic cardiomyopathy (DCM) is one of the main causes of mortality among diabetic patients, with oxidative stress and inflammation major contributors to its development. Dietary flavonoids show strong antioxidant and anti-inflammatory activities, although their potential additive outcomes in combination with antidiabetic drugs have been scarcely explored. The present study investigates the cardioprotective effects of a cocoa–carob blend (CCB) diet, rich in flavonoids, alone or in combination with metformin, in the development of DCM. Zucker diabetic fatty rats (ZDF) were fed with a CCB rich-diet or a control diet, with or without metformin for 12 weeks. Glucose homeostasis, cardiac structure and function, and oxidative and inflammatory biomarkers were analysed. CCB improved glucose homeostasis, and mitigated cardiac dysfunction, hypertrophy, and fibrosis in ZDF rats. Mechanistically, CCB counteracted oxidative stress in diabetic hearts by down-regulating NADPH oxidases, reducing reactive oxygen species (ROS) generation and modulating the sirtuin-1 (SIRT1)/ nuclear factor E2-related factor 2 (Nrf2) signalling pathway, overall improving antioxidant defence. Moreover, CCB suppressed inflammatory and fibrotic reactions by inhibiting nuclear factor kappa B (NFκB) and pro-inflammatory and pro-fibrotic cytokines. Noteworthy, several of these effects were further improved in combination with metformin. Our results demonstrate that CCB strongly prevents the cardiac remodelling and dysfunction observed in diabetic animals, highlighting its potential, alone or in adjuvant therapy, for treating DCM.

Endothelial small- and intermediate-conductance KCa channels, SK3 and IK1, are key mediators in the endothelium-derived hyperpolarization and relaxation of vascular smooth muscle and also in the modulation of endothelial Ca2+ signaling and nitric oxide (NO) release. Obesity is associated with endothelial dysfunction and impaired relaxation, although how obesity influences endothelial SK3/IK1 function is unclear. Therefore we assessed whether the role of these channels in the coronary circulation is altered in obese animals. In coronary arteries mounted in microvascular myographs, selective blockade of SK3/IK1 channels unmasked an increased contribution of these channels to the ACh- and to the exogenous NO- induced relaxations in arteries of Obese Zucker Rats (OZR) compared to Lean Zucker Rats (LZR). Relaxant responses induced by the SK3/IK1 channel activator NS309 were enhanced in OZR and NO- endothelium-dependent in LZR, whereas an additional endothelium-independent relaxant component was found in OZR. Fura2-AM fluorescence revealed a larger ACh-induced intracellular Ca2+ mobilization in the endothelium of coronary arteries from OZR, which was inhibited by blockade of SK3/IK1 channels in both LZR and OZR. Western blot analysis showed an increased expression of SK3/IK1 channels in coronary arteries of OZR and immunohistochemistry suggested that it takes place predominantly in the endothelial layer. Obesity may induce activation of adaptive vascular mechanisms to preserve the dilator function in coronary arteries. Increased function and expression of SK3/IK1 channels by influencing endothelial Ca2+ dynamics might contribute to the unaltered endothelium-dependent coronary relaxation in the early stages of obesity.

Purpose of Review The present review focuses in the hypertension-associated changes in the microbiota and the current insights regarding the impact of probiotics on blood pressure in animal models and in human hypertensive patients. Recent Findings Gut dysbiosis in hypertension is characterized by (i) the gut microbioma that is less diverse and less rich with an increased Firmicutes / Bacteroidetes ratio and (ii) a decrease in acetate- and butyrate-producing bacteria and an increase in lactate-producing bacterial populations. The meta-analysis of the human studies supports that supplementation with probiotics reduces blood pressure. The mechanism of this antihypertensive effect of probiotics and its protective effect on endothelial function has not been fully elucidated. Summary Further investigations are needed to clarify if the effects of probiotic bacteria result from the changes in the gut microbiota and its metabolic by-products; the restoration of the gut barrier function; and the effects on endotoxemia, inflammation, and renal sympathetic nerve activity.

There is a lack of biomarkers of sepsis and the resuscitation status. Our objective was to prove that the serum expression of certain microribonucleic acids (miRNAs) is differentially regulated in sepsis and is sensitive to different resuscitation regimes. Anesthetized pigs (Sus scrofa domesticus) received no treatment (n = 15) or intravenous live E. coli (n = 24). The septic animals received 0.9% saline at 4 mL/kg/h (n = 8) (low resuscitation group (LoR)) or 10–17 mL/kg/h (high resuscitation group (HiR)) (n = 8 each group). Blood samples were obtained at the end of the experiment for measurement of seven different miRNAs (RT-qPCR, Qiagen, Hilden, Germany). The serum expression of miR-146a-5p and miR-34a-5p increased significantly in the septic group, and miR-146a-5p was significantly lower in the HiR group than in the LoR group. The toll-like receptor signaling pathway involving 22 target proteins was significantly (adjusted p = 3.87 × 10−4) regulated by these two microRNAs (KEGG). Highly significant (p value = 2.22 × 10−16) protein–protein interactions (STRING) were revealed for these 22 hits. MiR-146a-5p and miR-34a-5p were identified as biomarkers of sepsis, and miRNA146a-5p seemed to be a biomarker of the intensity of the resuscitation.

Only a limited proportion of patients needing pharmacological control of portal hypertension are hemodynamic responders to propranolol. Here we analyzed the effects of zolmitriptan on portal pressure and its potential interaction with propranolol. ZOLMITRIPTAN, PROPRANOLOL OR BOTH WERE TESTED IN TWO RAT MODELS OF PORTAL HYPERTENSION: common bile duct ligation (CBDL) and CCl4-induced cirrhosis. In these animals we measured different hemodynamic parameters including portal venous pressure, arterial renal flow, portal blood flow and cardiac output. We also studied the changes in superior mesenteric artery perfusion pressure and in arterial wall cAMP levels induced by zolmitriptan, propranolol or both. Moreover, we determined the effect of splanchnic sympathectomy on the response of PVP to zolmitriptan. In both models of portal hypertension zolmitriptan induced a dose-dependent transient descent of portal pressure accompanied by reduction of portal flow with only slight decrease in renal flow. In cirrhotic rats, splanchnic sympathectomy intensified and prolonged zolmitriptan-induced portal pressure descent. Also, propranolol caused more intense and durable portal pressure fall when combined with zolmitriptan. Mesenteric artery perfusion pressure peaked for about 1 min upon zolmitriptan administration but showed no change with propranolol. However propranolol enhanced and prolonged the elevation in mesenteric artery perfusion pressure induced by zolmitriptan. In vitro studies showed that propranolol prevented the inhibitory effects of β2-agonists on zolmitriptan-induced vasoconstriction and the combination of propranolol and zolmitriptan significantly reduced the elevation of cAMP caused by β2-agonists. Zolmitriptan reduces portal hypertension and non-selective beta-blockers can improve this effect. Combination therapy deserves consideration for patients with portal hypertension failing to respond to non-selective beta-blockers.

The effects of an oral daily dose (10 mg kg−1) of the flavonoid quercetin for 5 weeks in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY) were analysed. Quercetin induced a significant reduction in systolic (−18%), diastolic (−23%) and mean (−21%) arterial blood pressure and heart rate (−12%) in SHR but not in WKY rats. The left ventricular weight index and the kidney weight index in vehicle‐treated SHR were significantly greater than in control WKY and these parameters were significantly reduced in quercetin‐treated SHR in parallel with the reduction in systolic blood pressure. Quercetin had no effect on the vasodilator responses to sodium nitroprusside or to the vasoconstrictor responses to noradrenaline or KCl but enhanced the endothelium‐dependent relaxation to acetylcholine (Emax=58±5%vs 78±5%, P<0.01) in isolated aortae. The 24 h urinary isoprostane F2α excretion and the plasma malonyldialdehyde (MDA) levels in SHR rats were increased as compared to WKY rats. However, in quercetin‐treated SHR rats both parameters were similar to those of vehicle‐treated WKY. These data demonstrate that quercetin reduces the elevated blood pressure, the cardiac and renal hypertrophy and the functional vascular changes in SHR rats without effect on WKY. These effects were associated with a reduced oxidant status due to the antioxidant properties of the drug. British Journal of Pharmacology (2001) 133, 117–124; doi:10.1038/sj.bjp.0704064

We have compared the mechanisms involved in sodium nitroprusside (SNP)‐induced relaxation and [Ca2+]i reduction in isolated piglet pulmonary (PA) and mesenteric (MA) arteries. SNP (10−8 M−3×10−5 M) evoked a concentration‐dependent relaxation of PA and MA (pD2=6.66±0.06 and 6.74±0.14, respectively) stimulated by noradrenaline, which was markedly reduced by the guanylate cyclase inhibitor ODQ. In fura 2‐incubated PA and MA, SNP produced a parallel reduction in contractile force and in [Ca2+]i, expressed as the ratio of emitted fluorescence at 340 and 380 nm (F340/F380). The inhibition of the Na+/K+‐ATPase after the incubation in a K+‐free medium or the exposure to ouabain (10−6 M) inhibited SNP‐induced relaxation in MA but not in PA. SNP‐induced relaxation was not attenuated by 80 mM KCl plus nifedipine (10−6 M) but was inhibited by thapsigargin (2×10−6 M; pD2=5.69±0.19 and 5.89±0.19 for PA and MA, respectively). Pretreatment of PA with thapsigargin and MA with thapsigargin plus ouabain induced a stronger inhibition on the reduction in [Ca2+]i than on the relaxation induced by SNP, indicating the existence of Ca2+‐independent mechanisms. The activation of the Na+/K+‐ATPase by the addition of KCl after the incubation in a K+‐free medium similarly reduced [Ca2+]i in PA and MA, whereas it relaxed with much less efficacy PA than MA. We conclude that SNP reduces [Ca2+]i and causes relaxation through the activation of SERCA in PA and SERCA and Na+/K+‐ATPase in MA. However, Ca2+‐independent mechanisms also contribute to SNP‐induced effects. British Journal of Pharmacology (2001) 132, 959–967; doi:10.1038/sj.bjp.0703894

Inhaled nitric oxide (iNO) is widely used in the treatment of pulmonary hypertension while inhaled NO donors have been suggested as an alternative therapy. The differential susceptibility to inactivation by oxidative stress and oxyhaemoglobin of NO and two NO donors, sodium nitroprusside (SNP) and S‐nitroso‐N‐acetyl‐penicillamine (SNAP) were analysed in isolated endothelium‐denuded pulmonary arteries from 2‐week‐old piglets stimulated with U46619. NO, SNAP and SNP relaxed the arteries (pIC30=7.73±0.12, 7.26±0.17 and 6.43±0.13, respectively) but NO was not detected electrochemically in the bath after the addition of SNP and only at concentrations at which SNAP produced more than 50% relaxation. The sGC inhibitor ODQ (10−6 M) or the sarcoplasmic Ca2+‐ATPase thapsigargin (2×10−6 M) markedly inhibited the relaxation induced by NO, SNAP and SNP. Addition of oxyhaemoglobin (3×10−7 M) or diethyldithiocarbamate (1 mM) markedly inhibited NO‐ (pIC30=6.88±0.07 and 6.92±0.18, respectively), weakly inhibited SNAP‐ and had no effect on SNP‐induced relaxation. Xanthine oxidase (5 mu ml−1) plus hypoxanthine (10−4 M) markedly inhibited NO‐ (pIC30=6.96±0.12) but not SNAP‐ or SNP‐induced relaxation. Superoxide dismutase (SOD), MnCl2, diphenileneiodonium and exposing the luminal surface of the rings outwards (inversion) potentiated the relaxant responses of NO (pIC30=8.52±0.16, 8.23±0.11, 8.01±0.11 and 8.20±0.10, respectively). However, SOD did not modify the NO detected by the electrode and had no effect on SNAP‐ or SNP‐induced relaxation. Therefore, the kinetics and local distribution of NO release of NO donors influence the susceptibility to the scavenging effects of oxyhaemoglobin and superoxide. British Journal of Pharmacology (2001) 133, 615–624; doi:10.1038/sj.bjp.0704103

Hepatocytes release extracellular vesicles (EVs) loaded with signaling molecules and enzymes into the bloodstream. Although the importance of EVs in the intercellular communication is already recognized, the metabolic impact of the enzymes carried by these vesicles is still unclear. We evaluated the global effect of the enzymatic activities of EVs by performing untargeted metabolomic profiling of serum samples after their exposure to EVs. This approach revealed a significant change in the abundance of 94 serum metabolic signals. Our study shows that these vesicles modify the concentration of metabolites of different chemical nature including metabolites related to arginine metabolism, which regulates vascular function. To assess the functional relevance of this finding, we examined the levels of arginase-1 protein and its activity in the hepatic EVs carrying the exosomal markers CD81 and CD63. Remarkably, the arginase activity was also detected in EVs isolated from the serum in vivo , and this vesicular activity significantly increased under liver-damaging conditions. Finally, we demonstrated that EVs secreted by hepatocytes inhibited the acetylcholine-induced relaxation in isolated pulmonary arteries, via an arginase-dependent mechanism. In summary, our study demonstrates that the hepatocyte-released EVs are metabolically active, affecting a number of serum metabolites involved in oxidative stress metabolism and the endothelial function.