Analysis of cardiohemodynamic and electrophysiological effects of morphine along with its toxicokinetic profile using the halothane-anesthetized dogs.

Although morphine has been used for treatment-resistant dyspnea in end-stage heart failure patients, information on its cardiovascular safety profile remains limited. Morphine was intravenously administered to halothane-anesthetized dogs (n=4) in doses of 0.1, 1 and 10 mg/kg/10 min with 20 min of observation period. The low and middle doses attained therapeutic (0.13 µg/mL) and supratherapeutic (0.97 µg/mL) plasma concentrations, respectively. The low dose hardly altered any of the cardiovascular variables except that the QT interval was prolonged for 10-15 min after its start of infusion. The middle dose reduced the preload and afterload to the left ventricle for 5-15 min, then decreased the left ventricular contractility and mean blood pressure for 10-30 min, and finally suppressed the heart rate for 15-30 min. Moreover, the middle dose gradually but progressively prolonged the atrioventricular conduction time, QT interval/QTcV, ventricular late repolarization period and ventricular effective refractory period without altering the intraventricular conduction time, ventricular early repolarization period or terminal repolarization period. A reverse-frequency-dependent delay of ventricular repolarization was confirmed. The high dose induced cardiohemodynamic collapse mainly due to vasodilation in the initial 2 animals by 1.9 and 3.3 min after its start of infusion, respectively, which needed circulatory support to treat. The high dose was not tested further in the remaining 2 animals. Thus, intravenously administered morphine exerts a rapidly appearing vasodilator action followed by slowly developing cardiosuppressive effects. Morphine can delay the ventricular repolarization possibly through IKr inhibition in vivo, but its potential to develop torsade de pointes will be small.

Isoflurane increases the activity of the vascular matrix metalloproteinase-2 in non-pregnant rats and increases the nitric oxide metabolites in pregnancy.

Surgeries that require general anesthesia occur in 1.5-2% of gestations. Isoflurane is frequently used because of its lower possibility of affecting fetal growth. Therefore, we examined the isoflurane anesthesia-induced effects on maternal hemodynamic and vascular changes. We hypothesized that isoflurane would enhance endothelium-dependent vasodilation as a consequence of increased nitric oxide and decreased metalloproteinases (MMPs). Female rats (n=28) were randomized into 4 groups (7 rats/group): conscious (non-anesthetized) non-pregnant group, non-pregnant anesthetized group, conscious pregnant group, and pregnant anesthetized group. Anesthesia was performed on the 20th pregnancy day, and hemodynamic parameters were monitored. Nitric oxide metabolites, gelatinolytic activity of MMP-2 and MMP-9, and the vascular function were assessed. Isoflurane caused no significant hemodynamic changes in pregnant compared with non-pregnant anesthetized group. Impaired acetylcholine-induced relaxations were observed only in conscious non-pregnant group (by approximately 62%) versus 81% for other groups. Phenylephrine-induced contractions were greater in endothelium-removed aorta segments of both pregnant groups (with or without isoflurane) compared with non-pregnant groups. Higher nitric oxide metabolites were observed in anesthetized pregnant in comparison with the other groups. Reductions in the 75 kDa activity and concomitant increases in 64 kDa MMP-2 isoforms were observed in aortas of pregnant anesthetized (or not) groups compared with conscious non-pregnant group. Isoflurane anesthesia shows stable effects on hemodynamic parameters and normal MMP-2 activation in pregnancy. Furthermore, there were increases in nitric oxide bioavailability, suggesting that isoflurane provides protective actions to the endothelium in pregnancy.

17-ß-estradiol and phytoestrogens elicit NO production and vasodilatation through PI3K, PKA and EGF receptors pathways, evidencing functional selectivity.

Endothelial cells express multiple receptors mediating estrogen responses; including the G protein-coupled estrogen receptor (GPER). Past studies on nitric oxide (NO) production elicited by estrogens raised the question whether 17-ß-estradiol (E2) and natural phytoestrogens activate equivalent mechanisms. We hypothesized that E2 and phytoestrogens elicit NO production via coupling to distinct intracellular pathways signalling. To this aim, perfusion of E2 and phytoestrogens to the precontracted rat mesentery bed examined vasorelaxation, while fluorescence microscopy on primary endothelial cells cultures quantified single cell NO production determined following 4-amino-5-methylamino-2',7'-difluoroescein diacetate (DAF) incubation. Daidzein (DAI) and genistein (GEN) induced rapid vasodilatation associated to NO production. Multiple estrogen receptor activity was inferred based on the reduction of DAF-NO signals; G-36 (GPER antagonist) reduced 75 % of all estrogen responses, while fulvestrant (selective nuclear receptor antagonist) reduced significantly more the phytoestrogens responses than E2. The joint application of both antagonists abolished the E2 response but not the phytoestrogen-induced DAF-NO signals. Wortmannin or LY-294002 (PI3K inhibitors), reduced by 90% the E2-evoked signal while altering significantly less the DAI-induced response. In contrast, H-89 (PKA inhibitor), elicited a 23% reduction of the E2-induced signal while blocking 80% of the DAI-induced response. Desmethylxestospongin-B (IP3 receptor antagonist), decreased to equal extent the E2 or the DAI-induced signal. Epidermal growth factor (EGF) induced NO production, cell treatment with AG-1478, an EGF receptor kinase inhibitor reduced 90% DAI-induced response while only 53% the E2-induced signals; highlighting GPER induced EGF receptor trans-modulation. Receptor functional selectivity may explain distinct signalling pathways mediated by E2 and phytoestrogens.

Vascular Response of Triiodothyronine on Isolated Aortic Rings: Contribution of Redox Mechanisms. / Resposta Vascular da Triiodotironina sobre Anéis de Aortas Isoladas: Contribuição de Mecanismos Redox.

BACKGROUND: Vascular dysfunction constitutes the etiology of many diseases, such as myocardial infarction and hypertension, with the disruption of redox homeostasis playing a role in the imbalance of the vasomotor control mechanism. Our group previously has shown that thyroid hormones exert protective effects on the aortic tissue of infarcted rats by improving angiogenesis signaling. OBJECTIVE: Investigate the role of triiodothyronine (T3) on vascular response, exploring its effects on isolated aortas and whether there is an involvement of vascular redox mechanisms. METHODS: Isolated aortic rings (intact- and denuded-endothelium) precontracted with phenylephrine were incubated with T3 (10-8, 10-7, 10-6, 10-5, and 10-4 M), and tension was recorded using a force-displacement transducer coupled with an acquisition system. To assess the involvement of oxidative stress, aortic rings were preincubated with T3 and subsequently submitted to an in vitro reactive oxygen species (ROS) generation system. The level of significance adopted in the statistical analysis was 5%. RESULTS: T3 (10-4 M) promoted vasorelaxation of phenylephrine precontracted aortic rings in both intact- and denuded-endothelium conditions. Aortic rings preincubated in the presence of T3 (10-4 M) also showed decreased vasoconstriction elicited by phenylephrine (1 µM) in intact-endothelium preparations. Moreover, T3 (10-4 M) vasorelaxation effect persisted in aortic rings preincubated with NG-nitro-L-arginine methylester (L-NAME, 10 µM), a nonspecific NO synthase (NOS) inhibitor. Finally, T3 (10-4 M) exhibited, in vitro, an antioxidant role by reducing NADPH oxidase activity and increasing SOD activity in the aorta's homogenates. CONCLUSION: T3 exerts dependent- and independent-endothelium vasodilation effects, which may be related to its role in maintaining redox homeostasis.

FUNDAMENTO: A disfunção vascular constitui a etiologia de diversas doenças, incluindo infarto do miocárdio e hipertensão, diante da ruptura da homeostase oxi-redutiva ("redox"), desempenhando um papel no desequilíbrio do mecanismo de controle vasomotor. Nosso grupo demonstrou anteriormente que os hormônios tireoidianos melhoram a sinalização da angiogênese, exercendo efeitos protetores sobre o tecido aórtico de ratos infartados. OBJETIVOS: Investigar o papel da triiodotironina (T3) na resposta vascular, explorando seus efeitos em aortas isoladas e a presença de mecanismos redox vasculares. MÉTODOS: Anéis aórticos isolados (endotélio intacto e desnudado) pré-contraídos com fenilefrina foram incubados com T3 (10-8, 10-7, 10-6, 10-5 e 10-4 M) e a tensão foi registrada usando um transdutor de deslocamento de força acoplado a um sistema de coleta. Para avaliar o envolvimento do estresse oxidativo, os anéis aórticos foram pré-incubados com T3 e posteriormente submetidos a um sistema de geração de espécies reativas de oxigênio (ROS) in vitro. O nível de significância adotado na análise estatística foi de 5%. RESULTADOS: A T3 (10-4 M) promoveu o vasorrelaxamento dos anéis aórticos pré-contraídos com fenilefrina em endotélio intacto e desnudado. Os anéis aórticos pré-incubados na presença de T3 (10-4 M) também mostraram diminuição da vasoconstrição provocada pela fenilefrina (1 µM) em preparações de endotélio intacto. Além disso, o efeito vasorrelaxante da T3 (10-4 M) persistiu em anéis aórticos pré-incubados com éster metílico de NG-nitro-L-arginina (L-NAME, 10 µM), um inibidor inespecífico da NO sintase (NOS). Por fim, a T3 (10-4 M) exibiu, in vitro, um papel antioxidante ao reduzir a atividade da NADPH oxidase e aumentar a atividade da SOD nos homogenatos aórticos. CONCLUSÃO: A T3 exerce efeitos dependentes e independentes de endotélio, o que pode estar relacionado ao seu papel na manutenção da homeostase redox.

Vasorelaxant and Blood Pressure-Lowering Effects of Cnidium monnieri Fruit Ethanol Extract in Sprague Dawley and Spontaneously Hypertensive Rats.

Cnidium monnieri (L.) Cusson, a member of the Apiaceae family, is rich in coumarins, such as imperatorin and osthole. Cnidium monnieri fruit (CM) has a broad range of therapeutic potential that can be used in anti-bacterial, anti-cancer, and sexual dysfunction treatments. However, its efficacy in lowering blood pressure through vasodilation remains unknown. This study aimed to assess the potential therapeutic effect of CM 50% ethanol extract (CME) on hypertension and the mechanism of its vasorelaxant effect. CME (1-30 µg/mL) showed a concentration-dependent vasorelaxation on constricted aortic rings in Sprague Dawley rats induced by phenylephrine via an endothelium-independent mechanism. The vasorelaxant effect of CME was inhibited by blockers of voltage-dependent and Ca2+-activated K+ channels. Additionally, CME inhibited the vascular contraction induced by angiotensin II and CaCl2. The main active compounds of CM, i.e., imperatorin (3-300 µM) and osthole (1-100 µM), showed a concentration-dependent vasorelaxation effect, with half-maximal effective concentration values of 9.14 ± 0.06 and 5.98 ± 0.06 µM, respectively. Orally administered CME significantly reduced the blood pressure of spontaneously hypertensive rats. Our research shows that CME is a promising treatment option for hypertension. However, further studies are required to fully elucidate its therapeutic potential.

The Effect of an Elevated Dietary Copper Level on the Vascular Contractility and Oxidative Stress in Middle-Aged Rats.

Copper (Cu), being an essential mineral, plays a crucial role in maintaining physiological homeostasis across multiple bodily systems, notably the cardiovascular system. However, an increased Cu level in the body may cause blood vessel dysfunction and oxidative stress, which is unfavorable for the cardiovascular system. Middle-aged (7-8 months old) male Wistar rats (n/group = 12) received a diet supplemented with 6.45 mg Cu/kg (100% of the recommended daily dietary quantity of copper) for 8 weeks (Group A). The experimental group received 12.9 mg Cu/kg of diet (200%-Group B). An ex vivo study revealed that supplementation with 200% Cu decreased the contraction of isolated aortic rings to noradrenaline (0.7-fold) through FP receptor modulation. Vasodilation to sodium nitroprusside (1.10-fold) and acetylcholine (1.13-fold) was potentiated due to the increased net effect of prostacyclin derived from cyclooxygenase-1. Nitric oxide (NO, 2.08-fold), superoxide anion (O2•-, 1.5-fold), and hydrogen peroxide (H2O2, 2.33-fold) measured in the aortic rings increased. Blood serum antioxidant status (TAS, 1.6-fold), Cu (1.2-fold), Zn (1.1-fold), and the Cu/Zn ratio (1.4-fold) increased. An increase in Cu (1.12-fold) and the Cu/Zn ratio (1.09-fold) was also seen in the rats' livers. Meanwhile, cyclooxygenase-1 (0.7-fold), cyclooxygenase-2 (0.4-fold) and glyceraldehyde 3-phosphate dehydrogenase (0.5-fold) decreased. Moreover, a negative correlation between Cu and Zn was found (r = -0.80) in rat serum. Supplementation with 200% Cu did not modify the isolated heart functioning. No significant difference was found in the body weight, fat/lean body ratio, and organ weight for either the heart or liver, spleen, kidney, and brain. Neither Fe nor Se, the Cu/Se ratio, the Se/Zn ratio (in serum and liver), heme oxygenase-1 (HO-1), endothelial nitric oxide synthase (eNOS), or intercellular adhesion molecule-1 (iCAM-1) (in serum) were modified. Supplementation with 200% of Cu potentiated pro-oxidant status and modified vascular contractility in middle-aged rats.

Effect of Coenzyme Q10 Supplementation on Vascular Endothelial Function: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

INTRODUCTION: Coenzyme Q10 (CoQ10) has gained attention as a potential therapeutic agent for improving endothelial function. Several randomized clinical trials have investigated CoQ10 supplementation's effect on endothelial function. However, these studies have yielded conflicting results, therefore this systematic review and meta-analysis were conducted. AIM: This systematic review and meta-analysis were conducted to assess the effects of CoQ10 supplementation on endothelial factors. METHODS: A comprehensive search was done in numerous databases until July 19th, 2023. Quantitative data synthesis was performed using a random-effects model, with weight mean difference (WMD) and 95% confidence intervals (CI). Standard methods were used for the assessment of heterogeneity, meta-regression, sensitivity analysis, and publication bias. RESULTS: 12 studies comprising 489 subjects were included in the meta-analysis. The results demonstrated significant increases in Flow Mediated Dilation (FMD) after CoQ10 supplementation (WMD: 1.45; 95% CI: 0.55 to 2.36; p < 0.02), but there is no increase in Vascular cell adhesion protein (VCAM), and Intercellular adhesion molecule (ICAM) following Q10 supplementation (VCAM: SMD: - 0.34; 95% CI: - 0.74 to - 0.06; p < 0.10) (ICAM: SMD: - 0.18; 95% CI: - 0.82 to 0.46; p < 0.57). The sensitivity analysis showed that the effect size was robust in FMD and VCAM. In meta-regression, changes in FMD percent were associated with the dose of supplementation (slope: 0.01; 95% CI: 0.004 to 0.03; p = 0.006). CONCLUSIONS: CoQ10 supplementation has a positive effect on FMD in a dose-dependent manner. Our findings show that CoQ10 has an effect on FMD after 8 weeks of consumption. Additional research is warranted to establish the relationship between CoQ10 supplementation and endothelial function.

The antidiabetic drug ipragliflozin induces vasorelaxation of rabbit femoral artery by activating a Kv channel, the SERCA pump, and the PKA signaling pathway.

We explored the vasorelaxant effects of ipragliflozin, a sodium-glucose cotransporter-2 inhibitor, on rabbit femoral arterial rings. Ipragliflozin relaxed phenylephrine-induced pre-contracted rings in a dose-dependent manner. Pre-treatment with the ATP-sensitive K+ channel inhibitor glibenclamide (10 µM), the inwardly rectifying K+ channel inhibitor Ba2+ (50 µM), or the Ca2+-sensitive K+ channel inhibitor paxilline (10 µM) did not influence the vasorelaxant effect. However, the voltage-dependent K+ (Kv) channel inhibitor 4-aminopyridine (3 mM) reduced the vasorelaxant effect. Specifically, the vasorelaxant response to ipragliflozin was significantly attenuated by pretreatment with the Kv7.X channel inhibitors linopirdine (10 µM) and XE991 (10 µM), the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin (1 µM) and cyclopiazonic acid (10 µM), and the cAMP/protein kinase A (PKA)-associated signaling pathway inhibitors SQ22536 (50 µM) and KT5720 (1 µM). Neither the cGMP/protein kinase G (PKG)-associated signaling pathway nor the endothelium was involved in ipragliflozin-induced vasorelaxation. We conclude that ipragliflozin induced vasorelaxation of rabbit femoral arteries by activating Kv channels (principally the Kv7.X channel), the SERCA pump, and the cAMP/PKA-associated signaling pathway independent of other K+ (ATP-sensitive K+, inwardly rectifying K+, and Ca2+-sensitive K+) channels, cGMP/PKG-associated signaling, and the endothelium.

Short-Chain Fatty Acid Butyrate Is an Inotropic Agent With Vasorelaxant and Cardioprotective Properties.

BACKGROUND: The heart can metabolize the microbiota-derived short-chain fatty acid butyrate. Butyrate may have beneficial effects in heart failure, but the underlying mechanisms are unknown. We tested the hypothesis that butyrate elevates cardiac output by mechanisms involving direct stimulation of cardiac contractility and vasorelaxation in rats. METHODS AND RESULTS: We examined the effects of butyrate on (1) in vivo hemodynamics using parallel echocardiographic and invasive blood pressure measurements, (2) isolated perfused hearts in Langendorff systems under physiological conditions and after ischemia and reperfusion, and (3) isolated coronary arteries mounted in isometric wire myographs. We tested Na-butyrate added to injection solutions or physiological buffers and compared its effects with equimolar doses of NaCl. Butyrate at plasma concentrations of 0.56 mM increased cardiac output by 48.8±14.9%, stroke volume by 38.5±12.1%, and left ventricular ejection fraction by 39.6±6.2%, and lowered systemic vascular resistance by 33.5±6.4% without affecting blood pressure or heart rate in vivo. In the range between 0.1 and 5 mM, butyrate increased left ventricular systolic pressure by up to 23.7±3.4% in isolated perfused hearts and by 9.4±2.9% following ischemia and reperfusion, while reducing myocardial infarct size by 81.7±16.9%. Butyrate relaxed isolated coronary septal arteries concentration dependently with an EC50=0.57 mM (95% CI, 0.23-1.44). CONCLUSIONS: We conclude that butyrate elevates cardiac output through mechanisms involving increased cardiac contractility and vasorelaxation. This effect of butyrate was not associated with adverse myocardial injury in damaged hearts exposed to ischemia and reperfusion.

Effects of BNT162b2 mRNA Covid-19 vaccine on vascular function.

The effects of Covid-19 vaccines on vascular function are still controversial. We evaluated the effects of BNT162b2 vaccine (BioNTech and Pfizer) on endothelial function assessed by flow-mediated vasodilation (FMD) and vascular smooth muscle function assessed by nitroglycerine-induced vasodilation (NID). This study was a prospective observational study. A total of 23 medical staff at Hiroshima University Hospital were enrolled in this study. FMD and NID were measured before vaccination and two weeks and six months after the 2nd dose of vaccination. FMD was significantly smaller two weeks after the 2nd dose of vaccination than before vaccination (6.5±2.4% and 8.2±2.6%, p = 0.03). FMD was significantly larger at six months than at two weeks after the 2nd dose of vaccination (8.2±3.0% and 6.5±2.4%, p = 0.03). There was no significant difference between FMD before vaccination and that at six months after the 2nd dose of vaccination (8.2±2.6% to 8.2±3.0%, p = 0.96). NID values were similar before vaccination and at two weeks, and six months after vaccination (p = 0.89). The BNT162b2 Covid-19 vaccine temporally impaired endothelial function but not vascular smooth muscle function, and the impaired endothelial function returned to the baseline level within six months after vaccination.

Deficiency of neutral cholesterol ester hydrolase 1 (NCEH1) impairs endothelial function in diet-induced diabetic mice.

BACKGROUND: Neutral cholesterol ester hydrolase 1 (NCEH1) plays a critical role in the regulation of cholesterol ester metabolism. Deficiency of NCHE1 accelerated atherosclerotic lesion formation in mice. Nonetheless, the role of NCEH1 in endothelial dysfunction associated with diabetes has not been explored. The present study sought to investigate whether NCEH1 improved endothelial function in diabetes, and the underlying mechanisms were explored. METHODS: The expression and activity of NCEH1 were determined in obese mice with high-fat diet (HFD) feeding, high glucose (HG)-induced mouse aortae or primary endothelial cells (ECs). Endothelium-dependent relaxation (EDR) in aortae response to acetylcholine (Ach) was measured. RESULTS: Results showed that the expression and activity of NCEH1 were lower in HFD-induced mouse aortae, HG-exposed mouse aortae ex vivo, and HG-incubated primary ECs. HG exposure reduced EDR in mouse aortae, which was exaggerated by endothelial-specific deficiency of NCEH1, whereas NCEH1 overexpression restored the impaired EDR. Similar results were observed in HFD mice. Mechanically, NCEH1 ameliorated the disrupted EDR by dissociating endothelial nitric oxide synthase (eNOS) from caveolin-1 (Cav-1), leading to eNOS activation and nitric oxide (NO) release. Moreover, interaction of NCEH1 with the E3 ubiquitin-protein ligase ZNRF1 led to the degradation of Cav-1 through the ubiquitination pathway. Silencing Cav-1 and upregulating ZNRF1 were sufficient to improve EDR of diabetic aortas, while overexpression of Cav-1 and downregulation of ZNRF1 abolished the effects of NCEH1 on endothelial function in diabetes. Thus, NCEH1 preserves endothelial function through increasing NO bioavailability secondary to the disruption of the Cav-1/eNOS complex in the endothelium of diabetic mice, depending on ZNRF1-induced ubiquitination of Cav-1. CONCLUSIONS: NCEH1 may be a promising candidate for the prevention and treatment of vascular complications of diabetes.

Combined cardiovascular effects of ovariectomy and high-intensity interval training in female spontaneously hypertensive rats.

Hypertensive postmenopausal women are more likely to develop adverse cardiac remodeling and respond less effectively to drug treatment than men. High-intensity interval exercise (HIIE) is a nonpharmacological strategy for the treatment of hypertension; however, the effectiveness in women remains uncertain. This study was designed to evaluate 1) the effects of HIIE training upon morphological and functional markers of cardiovascular health in female SHR and 2) to determine whether the hormonal shift induced by ovariectomy could influence cardiovascular responses to HIIE. Thirty-six SHR were randomly assigned to four groups: ovariectomized sedentary, ovariectomized trained, sham-operated sedentary, and sham-operated trained. The trained rats performed HIIE 5 days/wk for 8 wk. Blood pressure and echocardiographic measurements were performed before and after training in animals. Cardiac response to ß-adrenergic stimulation and the expression of calcium regulatory proteins and estrogen receptors in heart samples were assessed. Endothelium-dependent vasorelaxation in response to acetylcholine was evaluated in aortic rings as well as the expression of nitric oxide synthase isoforms (eNOS and P-eNOS) by Western blotting. In both groups of trained SHR, HIIE induced eccentric cardiac remodeling with greater inotropic and chronotropic effects, as well as an increase in SERCA and ß1AR expression. However, although the trained rats showed improved endothelial function and expression of eNOS and P-eNOS in the aorta, there was no demonstrated effect on blood pressure. In addition, the responses to HIIE training were not affected by ovariectomy. This work highlights the importance of assessing the cardiovascular efficacy and safety of different exercise modalities in women.NEW & NOTEWORTHY This study reports the effects of high-intensity interval exercise (HIIE) training on cardiac and endothelial function in female hypertensive rats. Despite a lack of effect on blood pressure (BP), HIIE training induces eccentric cardiac remodeling with greater functionals effects. Furthermore, training has beneficial effects on endothelial function. However, ovarian hormones do not seem to modulate cardiac and aortic adaptations to this training modality. All this underlines the need to consider training modalities on the cardiovascular system in women.

Acute effects of MitoQ on vascular endothelial function are influenced by cardiorespiratory fitness and baseline FMD in middle-aged and older adults.

A key mechanism promoting vascular endothelial dysfunction is mitochondrial-derived reactive oxygen species (mtROS). Aerobic exercise preserves endothelial function in preclinical models by lowering mtROS. However, the effects of mtROS on endothelial function in exercising and non-exercising adults is limited. In a double-blind, randomized, placebo-controlled crossover study design 23 (10 M/13 F, age 62.1 ± 11.5 years) middle-aged and older (MA/O, ≥45 years) adults were divided into two groups: exercisers (EX, n = 11) and non-exercisers (NEX, n = 12). All participants had endothelial function (brachial artery flow-mediated dilatation, FMDBA) measured before and ∼1 h after mitoquinone mesylate (MitoQ) (single dose, 80 mg) and placebo supplementation. A two-way repeated measures ANOVA was used to determine the effects of MitoQ and placebo on FMDBA. Pearson correlations assessed the association between the change in FMDBA with MitoQ and baseline FMDBA and cardiorespiratory fitness (CRF). Compared with placebo, MitoQ increased FMDBA in NEX by + 2.1% (MitoQ pre: 4.9 ± 0.4 vs. post: 7.0 ± 0.4 %, P = 0.004, interaction) but not in EX (P = 0.695, interaction). MitoQ also increased endothelial function in adults with a FMDBA <6% (P < 0.0001, interaction) but not >6% (P = 0.855, interaction). Baseline FMDBA and CRF were correlated (r = 0.44, P = 0.037), whereas the change in FMDBA with MitoQ was inversely correlated with CRF (r = -0.66, P < 0.001) and baseline FMDBA (r = -0.73, P < 0.0001). The relationship between the change in FMDBA and baseline FMDBA remained correlated after adjusting for CRF (r = -0.55, P = 0.007). These data demonstrate that MitoQ acutely improves FMDBA in NEX and EX adults who have a baseline FMDBA <6%. KEY POINTS: A key age-related change contributing to increased cardiovascular disease (CVD) risk is vascular endothelial dysfunction due to increased mitochondrial-derived reactive oxygen species (mtROS). Aerobic exercise preserves endothelial function via suppression of mtROS in preclinical models but the evidence in humans is limited. In the present study, a single dose of the mitochondria-targeted antioxidant, mitoquinone mesylate (MitoQ), increases endothelial function in non-exercisers with lower cardiorespiratory fitness (CRF) but not in exercisers with higher CRF. The acute effects of MitoQ on endothelial function in middle-aged and older adults (MA/O) are influenced by baseline endothelial function independent of CRF. These data provide initial evidence that the acute MitoQ-enhancing effects on endothelial function in MA/O adults are influenced, in part, via CRF and baseline endothelial function.

Effects of alirocumab on endothelial function and coronary atherosclerosis in myocardial infarction: A PACMAN-AMI randomized clinical trial substudy.

BACKGROUND AND AIMS: The effects of protein convertase subtilisin/kexin type 9 (PCSK9) inhibitors on endothelial function as assessed by flow-mediated dilation (FMD) in patients with acute myocardial infarction (AMI) are unknown. Therefore, we aimed to investigate the effects of the PCSK9 inhibitor alirocumab added to high-intensity statin on FMD, and its association with coronary atherosclerosis in non-infarct related arteries using intracoronary intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and optical coherence tomography (OCT). METHODS: This was a pre-specified substudy among patients recruited at Bern University Hospital, Switzerland, for the randomized-controlled, double-blind, PACMAN-AMI trial, which compared the effects of biweekly alirocumab 150 mg vs. placebo added to rosuvastatin. Brachial artery FMD was measured at 4 and 52 weeks, and intracoronary imaging at baseline and 52 weeks. RESULTS: 139/173 patients completed the substudy. There was no difference in FMD at 52 weeks in the alirocumab (n = 68, 5.44 ± 2.24%) versus placebo (n = 71, 5.45 ± 2.19%) group (difference = -0.21%, 95% CI -0.77 to 0.35, p = 0.47). FMD improved throughout 52 weeks in both groups similarly (p < 0.001). There was a significant association between 4 weeks FMD and baseline plaque burden (IVUS) (n = 139, slope = -1.00, p = 0.006), but not with lipid pool (NIRS) (n = 139, slope = -7.36, p = 0.32), or fibrous cap thickness (OCT) (n = 81, slope = -1.57, p = 0.62). CONCLUSIONS: Among patients with AMI, the addition of alirocumab did not result in further improvement of FMD as compared to 52 weeks secondary preventative medical therapy including high-intensity statin therapy. FMD was significantly associated with coronary plaque burden at baseline, but not with lipid pool or fibrous cap thickness.

The renal vasodilatation from ß-adrenergic activation in vivo in rats is not driven by KV7 and BKCa channels.

The mechanisms behind renal vasodilatation elicited by stimulation of ß-adrenergic receptors are not clarified. As several classes of K channels are potentially activated, we tested the hypothesis that KV7 and BKCa channels contribute to the decreased renal vascular tone in vivo and in vitro. Changes in renal blood flow (RBF) during ß-adrenergic stimulation were measured in anaesthetized rats using an ultrasonic flow probe. The isometric tension of segmental arteries from normo- and hypertensive rats and segmental arteries from wild-type mice and mice lacking functional KV7.1 channels was examined in a wire-myograph. The ß-adrenergic agonist isoprenaline increased RBF significantly in vivo. Neither activation nor inhibition of KV7 and BKCa channels affected the ß-adrenergic RBF response. In segmental arteries from normo- and hypertensive rats, inhibition of KV7 channels significantly decreased the ß-adrenergic vasorelaxation. However, inhibiting BKCa channels was equally effective in reducing the ß-adrenergic vasorelaxation. The ß-adrenergic vasorelaxation was not different between segmental arteries from wild-type mice and mice lacking KV7.1 channels. As opposed to rats, inhibition of KV7 channels did not affect the murine ß-adrenergic vasorelaxation. Although inhibition and activation of KV7 channels or BKCa channels significantly changed baseline RBF in vivo, none of the treatments affected ß-adrenergic vasodilatation. In isolated segmental arteries, however, inhibition of KV7 and BKCa channels significantly reduced the ß-adrenergic vasorelaxation, indicating that the regulation of RBF in vivo is driven by several actors in order to maintain an adequate RBF. Our data illustrates the challenge in extrapolating results from in vitro to in vivo conditions.

The role of T-type calcium channels in elderly human vascular function: A pilot randomized controlled trial.

Endothelial dysfunction develops with age and may precede cardiovascular disease. Animal data suggest that T-type calcium channels play an important role in endothelial function, but data from humans are lacking. This study included 15 healthy, sedentary, elderly males for a double blinded, randomized controlled trial. For 8 weeks, they were given 40 mg/day of either efonidipine (L- and T-type calcium channel blocker (CCB)) or nifedipine (L-type CCB). Vascular function was evaluated by graded femoral arterial infusions of acetylcholine (ACh; endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator) both with and without co-infusion of N-acetylcysteine (NAC; antioxidant). We measured leg blood flow and mean arterial pressure and calculated leg vascular conductance to evaluate the leg vascular responses. Despite no significant change in blood pressure in either group, we observed higher leg blood flow responses (Δ 0.43 ± 0.45 l/min, P = 0.006) and leg vascular conductance (Δ 5.38 ± 5.67 ml/min/mmHg, P = 0.005) to intra-arterial ACh after efonidipine, whereas there was no change in the nifedipine group, and no differences between groups. We found no upregulation of endothelial nitric oxide synthase in vastus lateralis muscle biopsies within or between groups. Smooth muscle cell responsiveness was unaltered by efonidipine or nifedipine. Intravenous co-infusion of NAC did not affect endothelium-dependent vasodilatation in either of the CCB groups. These results suggest that 8 weeks' inhibition of T- and L-type calcium channels augments endothelium-dependent vasodilatory function in healthy elderly males. Further studies are required to elucidate if T-type calcium channel inhibition can counteract endothelial dysfunction.

α acid fraction from Hop extract exerts an endothelium-derived hyperpolarization vasorelaxant effect through TRPV4 employing the feedforward mechanism of PKCα.

Until now, the beneficial vascular properties of Hop reported in the literature have been mainly attributed to specific compound classes, such as tannins and phenolic acids. However, the potential vascular action of a Hop subfraction containing a high amount of α or ß acids remains completely understood. Therefore, this study aims to investigate the vascular effects of the entire Hop extract and to fraction the Hop extract to identify the main bioactive vascular compounds. A pressure myograph was used to perform vascular reactivity studies on mouse resistance arteries. Phytocomplex fractionation was performed on a semi-prep HPLC system and characterized by UHPLC-PDA-MS/MS coupled to mass spectrometry. Western blot analysis was performed to characterize the phosphorylation site enrolled. The entire Hop extract exerts a direct dose-dependent endothelial vascular action. The B1 subfraction, containing a high concentration of α acids, recapitulates the vascular effect of the crude extract. Its vasorelaxant action is mediated by the opening of Transient Receptor Potential Vanilloid type 4 (TRPV4), potentiated by PKCα, and subsequent involvement of endothelial small-conductance calcium-activated potassium channels (SKCa) and intermediate-conductance calcium-activated potassium channels (IKCa) that drives endothelium-dependent hyperpolarization (EDH) through heterocellular myoendothelial gap junctions (MEGJs). This is the first comprehensive investigation of the vascular function of Hop-derived α acids in resistance arteries. Overall, our data suggest that the B1 subfraction from Hop extracts, containing only α acids, has great potential to be translated into the useful armamentarium of natural bioactive compounds with cardiovascular benefits.

Hydrogen sulfide dysfunction in metabolic syndrome-associated vascular complications involves cGMP regulation through soluble guanylyl cyclase persulfidation.

Here, by using in vitro and ex vivo approaches, we elucidate the impairment of the hydrogen sulfide (H2S) pathway in vascular complications associated with metabolic syndrome (MetS). In the in vitro model simulating hyperlipidemic/hyperglycemic conditions, we observe significant hallmarks of endothelial dysfunction, including eNOS/NO signaling impairment, ROS overproduction, and a reduction in CSE-derived H2S. Transitioning to an ex vivo model using db/db mice, a genetic MetS model, we identify a downregulation of CBS and CSE expression in aorta, coupled with a diminished L-cysteine-induced vasorelaxation. Molecular mechanisms of eNOS/NO signaling impairment, dissected using pharmacological and molecular approaches, indicate an altered eNOS/Cav-1 ratio, along with reduced Ach- and Iso-induced vasorelaxation and increased L-NIO-induced contraction. In vivo treatment with the H2S donor Erucin ameliorates vascular dysfunction observed in db/db mice without impacting eNOS, further highlighting a specific action on smooth muscle component rather than the endothelium. Analyzing the NO signaling pathway in db/db mice aortas, reduced cGMP levels were detected, implicating a defective sGC/cGMP signaling. In vivo Erucin administration restores cGMP content. This beneficial effect involves an increased sGC activity, due to enzyme persulfidation observed in sGC overexpressed cells, coupled with PDE5 inhibition. In conclusion, our study demonstrates a pivotal role of reduced cGMP levels in impaired vasorelaxation in a murine model of MetS involving an impairment of both H2S and NO signaling. Exogenous H2S supplementation through Erucin represents a promising alternative in MetS therapy, targeting smooth muscle cells and supporting the importance of lifestyle and nutrition in managing MetS.

Pharmacology of erenumab in human isolated coronary and meningeal arteries: Additional effect of gepants on top of a maximum effect of erenumab.

BACKGROUND AND PURPOSE: Multiple drugs targeting the calcitonin gene-related peptide (CGRP) receptor have been developed for migraine treatment. Here, the effect of the monoclonal antibody erenumab on CGRP-induced vasorelaxation was investigated in human isolated blood vessels, as well as the effect of combining erenumab with the small molecule drugs, namely rimegepant, olcegepant, or sumatriptan. EXPERIMENTAL APPROACH: Concentration-response curves to CGRP, adrenomedullin or pramlintide were constructed in human coronary artery (HCA) and human middle meningeal artery (HMMA) segments, incubated with or without erenumab and/or olcegepant. pA2 or pKb values were calculated to determine the potency of erenumab in both tissues. To study whether acutely acting antimigraine drugs exerted additional CGRP-blocking effects on top of erenumab, HCA segments were incubated with a maximally effective concentration of erenumab (3 µM), precontracted with KCl and exposed to CGRP, followed by rimegepant, olcegepant, or sumatriptan in increasing concentrations. KEY RESULTS: Erenumab shifted the concentration-response curve to CGRP in both vascular tissues. However, in HCA, the Schild plot slope was significantly smaller than unity, whereas this was not the case in HMMA, indicating different CGRP receptor mechanisms in these tissues. In HCA, rimegepant, olcegepant and sumatriptan exerted additional effects on CGRP on top of a maximal effect of erenumab. CONCLUSIONS AND IMPLICATIONS: Gepants have additional effects on top of erenumab for CGRP-induced relaxation and could be effective in treating migraine attacks in patients already using erenumab as prophylaxis.

Mitochondrial KATP channel-mediated autophagy contributes to angiotensin II-induced vascular dysfunction in mice.

BACKGROUND AND AIM: The present study aimed to investigate whether the mitochondrial KATP channel contributes to angiotensin II (Ang II)-induced vascular dysfunction, the development of hypertension, and atherosclerosis. METHODS AND RESULTS: ApoE (-/-) mice fed a high-fat diet were chronically infused with Ang II for eight weeks and concomitantly treated with losartan (ARB), apocynin, or 5-hydroxy decanoate (5-HD), or 3-methyladenine (3-MA). Systolic blood pressure was measured, and pathological changes of aortic or liver tissue were observed. Nitric oxide (NO), superoxide dismutase 2 (SOD2) levels and vasorelaxation rate were measured, and protein and mRNA expressions were examined by western blot and RT-PCR. Ang II-induced development of hypertension was suppressed not only by ARB, and apocynin but also by 5-HD or 3-MA. Ang II infusion decreased aortic NO production and relaxation, as well as SOD2 activity in liver, which were improved by all treatments. In addition, Ang II-induced activation of autophagy was suppressed by 5-HD in aortic tissue, furthermore, Ang II increases the atherosclerotic index in plasma and exacerbates the development of atherosclerosis by increases of fat deposition in the aorta and liver. Lipid metabolism-related mRNA expressions (LXR-α, LDLR, SRBI, Acca, and FASN) were changed by Ang II. Similarly, not only ARB, and apocynin, but also 5-HD and 3-MA suppressed Ang II-induced these changes. CONCLUSIONS: Our present findings evidence that mitochondrial KATP channel-mediated autophagy contributes to Ang II-induced vascular dysfunction, development of hypertension, and atherosclerosis.