Endothelium-dependent Responses Research Articles

Effect of esaxerenone on the onset of aortic endothelial dysfunction and circulating microparticles in type 1 diabetic male mice

Endothelial dysfunction exacerbates hypertension and other vascular complications in diabetes mellitus (DM). Circulating microparticles (MPs) and extracellular vesicles released in patients with DM have emerged as novel regulators of endothelial dysfunction. The obstruction of mineralocorticoid receptors (MRs) is a potential therapeutic approach to reduce cardiovascular complications. Their impact on the obstruction of MRs on circulating MPs and endothelial dysfunction in DM remains unclear. DM was induced in mice through a single intravenous dose of streptozotocin (STZ; 200 mg/kg). Esaxerenone (ESAX; 3 mg/kg/day), a MR blocker was administered via diet for 8 weeks. In this study, the aortas of the DM group showed the endothelial dysfunction and the administration of ESAX ameliorated the endothelial-dependent responses. Moreover, ESAX influences the impaired endothelial-dependent responses of DM-derived MPs. Interestingly, MP levels increased in DM whereas decreased after ESAX administration. In the aorta, the DM-derived MPs increased the expression of intercellular adhesion molecule-1 (ICAM-1). ESAX inhibited the adhesion of DM-derived MPs. Moreover, the ICAM-1 inhibitor A205804 shows similar effects as ESAX. These results indicate that the release and adhesion properties of MPs can be partially obstructed by ESAX via the ICAM-1 signaling pathway, which clarifies the other functions beyond the anti-hypertensive effects of ESAX.

Coronary microvascular dysfunction in postmenopausal minipigs with multiple risk factors

Abstract Background Coronary microvascular angina occurs in both men and women, however, the majority of patients are postmenopausal women with multiple cardiovascular risk factors, such as diabetes mellitus (DM), chronic kidney disease (CKD) and dyslipidemia. No treatment is available for coronary microvascular dysfunction, requiring more in depth knowledge on the mechanisms underlying this syndrome in this expanding group of patients. Purpose Here we studied microvascular function in vivo and and in vitro in isolated small coronary arteries, in post-menopausal miniswine with multiple cardiovascular risk factors. Methods DM (streptozotocin), hypercholesterolemia (HC, high fat, high sugar diet), CKD (renal artery embolization) and menopause (ovariectomy, OVX) were induced in 5 adult female minipigs (1.5-2 years old, ~40kg, DM+HC+CKD+OVX) for 6 months, while 11 healthy age- and weight-matched female minipigs on normal pig chow served as controls (Normal). At sacrifice, coronary flow reserve (CFR) in response to intracoronary infusion of adenosine was measured under anesthesia. Isolated small coronary arteries were used to study the endothelium-dependent response to bradykinin in the presence and absence of eNOS blockade with LNAME, and cyclooxygenase inhibition by indomethacin, and endothelium-independent response to the nitric oxide (NO) donor, SNAP. Results 6 months of sustained hyperglycemia (17.5±1.0 in DM+HC+CKD+OVX vs 8.2±0.9 mmol/l in Normal, P<0.05 by t-test), hypercholesterolemia (15.4±2.0 vs 1.7±0.1 mmol/l, P<0.05), renal dysfunction (NGAL: 205±72 vs 67±5 ng/ml, P<0.05) and low progesterone levels (13.1±5.7 in DM+HC+CKD+OVX vs 92.0±30.0 nmol/l in Normal, P=0.1) were accompanied by systemic inflammation (TNFα: 62±7 vs 47±1 pg/ml, P<0.05). CFR was significantly reduced in DM+HC+CKD+OVX as compared to the healthy animals (panel A). Coronary small arteries from DM+HC+CKD+OVX animals showed impaired endothelium-dependent vasodilation to bradykinin (panel B), which was mediated by a loss of NO (panels C & D). The loss of NO was partly compensated for by activation of the cyclooxygenase pathway, as indomethacin blunted the dilation to bradykinin in the DM+HC+CKD+OVX animals, but had no effect on the dilation to bradykinin in Normals (panels C & D). Endothelium-independent dilation to SNAP was also impaired in DM+HC+CKD+OVX animals, indicating blunted vascular smooth muscle responsiveness to nitric oxide (panel E). Conclusion Postmenopausal minipigs with multiple risk factors, displayed severe coronary microvascular dysfunction as evidenced by a significantly reduced coronary flow reserve and both reduced NO sensitivity/ production, indicating endothelial and smooth muscle cell dysfunction. Loss of NO-mediated vasodilation was partially compensated by activation of cyclooxygenase pathway. Such perturbations may contribute to reduced myocardial perfusion that is often observed in post-menopausal women with multiple cardiovascular risk factors.

Beneficial Effects of Cocoa Flavanols on Microvascular Responses in Young Men May Be Dependent on Ethnicity and Lifestyle.

Cocoa flavan-3-ols affect endothelium-dependent responses in resistance vessels and microcirculation has received little attention. We tested the effects of dark chocolate consumption (396 mg total flavanols/day for 3 days) in two Groups of 10 men (18-25 years; non-smokers) each comprising equal numbers of White European (WE) and South Asian (SA) ethnicity. In Group 1, dark chocolate did not affect reactive hyperaemia in forearm muscle, but augmented muscle dilatation evoked by acute mental stress, and reactive hyperaemia and acetylcholine (ACh)-evoked dilatation in cutaneous microcirculation. Conversely, in Group 2, chocolate did not affect cutaneous reactive hyperaemia or ACh-evoked dilatation, but these responses were blunted in Group 1 relative to Group 2. Further, when Groups 1 and 2 were combined, responses were blunted in SAs relative to WEs, augmented by chocolate in SAs only. In Group 2 individuals whose ACh-evoked dilatation was attenuated by nitric oxide synthase (NOS) inhibition, ACh-evoked dilatation was not altered after chocolate, but the attenuating effect of NOS inhibition was lost. Conversely, in Group 2 individuals whose ACh-evoked dilatation was enhanced by NOS inhibition, ACh-evoked dilatation was also augmented by chocolate. We propose that in resistance and microvessels of young men, cocoa flavan-3-ols preferentially augment endothelium-dependent dilator responses whose responses are depressed by familial and lifestyle factors more prevalent in SAs than Wes. Flavan-3-ols may facilitate the NOS pathway but also influence other endothelium-dependent dilators.

Juvenile primary hypertension is associated with attenuated macro- and microvascular dilator function independently of body weight.

Hypertension has become a global medical and public health issue even in childhood. It is well accepted that hypertension is associated with impaired endothelium-dependent vascular reactivity in adult patients. However, there is a lack of data on hypertension-related endothelial dysfunction in hypertensive children. Thus, present study aimed to evaluate the association of primary hypertension in the pediatric population with macro- and microvascular function, and to assess the potential role of oxidative stress in that connection. Fifty-two children were enrolled in this study; 26 normotensive (NT) and 26 with primary hypertension (HT), both sexes, 9-17 years old. In addition to anthropometric, hemodynamic and biochemical measurements, peripheral microvascular responses to occlusion (postocclusive reactive hyperemia, PORH), local heating (local thermal hyperemia, LTH), iontophoretically applied acetylcholine (AChID) and sodium nitroprusside (SNPID) were evaluated by laser Doppler flowmetry (LDF). Furthermore, brachial artery flow-mediated dilation (FMD) was measured and biomarker of oxidative stress was determined. PORH, AChID and LTH were impaired in hypertensive compared to normotensive children, while SNPID did not differ between groups. FMD was decreased in hypertensive compared to normotensive children. Serum concentration of 8- iso -PGF2α was significantly elevated in hypertensive compared to normotensive children. Even in childhood, primary hypertension is associated with attenuated endothelial function and reduced endothelium-dependent responses to various physiological stimuli. Juvenile hypertension is related to increased level of vascular oxidative stress. All changes are independent of BMI.

Coronary microvascular dysfunction in postmenopausal minipigs with multiple risk factors

Coronary microvascular angina occurs in both men and women, however, the majority of patients are postmenopausal women with multiple cardiovascular risk factors, such as diabetes mellitus (DM), chronic kidney disease (CKD) and dyslipidemia. No treatment is available for coronary microvascular dysfunction, requiring more in depth knowledge on the mechanisms underlying this syndrome in this expanding group of patients. Here we studied microvascular function in vivo and and in vitro in isolated small coronary arteries, in postmenopausal miniswine with multiple cardiovascular risk factors. DM (streptozotocin), hypercholesterolemia (HC, high fat, high sugar diet), CKD (renal artery embolization) and menopause (OVX) were induced in 5 adult female minipigs (1.5-2 years old, ±40kg, DM+HC+CKD+OVX) for 6 months, while 11 healthy female minipigs matched for age and weight, on normal pig chow served as controls (Control). At sacrifice, coronary flow reserve (CFR) in response to intracoronary infusion of adenosine was measured under anesthesia, and endothelium-dependent response to bradykinin in the presence and absence of eNOS blockade with LNAME, were studied in vitro in isolated small coronary arteries. 6 months of sustained hyperglycemia (17.5±1.0 in in DM+HC+CKD+OVX vs 8.2±0.9 mmol/l in Control), hypercholesterolemia (15.4±2.0 vs 1.7±0.1 mmol/l) and renal dysfunction (plasma total protein: 84±3 vs 72±1 g/l) were accompanied by systemic inflammation (TNFalpha: 62±7 vs 47±1 pg/ml, all p<0.05 by t-test). Coronary flow reserve was significantly reduced in animals with multiple risk factors (3.4±0.4 in DM+HC+CKD+OVX) as compared to the healthy animals (4.9±0.3 in Control, p<0.05). In vitro, coronary small arteries from DM+HC+CKD+OVX animals showed impaired endothelium-dependent vasodilation to bradykinin, which was mediated by a loss of nitric oxide. Conclusion: Postmenopausal minipigs with multiple risk factors, displayed severe coronary microvascular dysfunction as evidenced by a significantly reduced coronary flow reserve and endothelial dysfunction. The latter was characterized by a marked loss of nitric oxide. Such perturbations may contribute to reduced myocardial perfusion that is often observed in postmenopausal women with multiple cardiovascular risk factors. Funding: Grant 2020B008 RECONNEXT. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Visceral adipose of obese mice inhibits endothelial inwardly rectifying K+ channels in a CD36-dependent fashion.

Obesity imposes deficits on adipose tissue and vascular endothelium, yet the role that distinct adipose depots play in mediating endothelial dysfunction in local arteries remains unresolved. We recently showed that obesity impairs endothelial Kir2.1 channels, mediators of nitric oxide production, in arteries of visceral adipose tissue (VAT), while Kir2.1 function in subcutaneous adipose tissue (SAT) endothelium remains intact. Therefore, we determined if VAT versus SAT from lean or diet-induced obese mice affected Kir2.1 channel function in vitro. We found that VAT from obese mice reduces Kir2.1 function without altering channel expression whereas AT from lean mice and SAT from obese mice had no effect on Kir2.1 function as compared to untreated control cells. As Kir2.1 is well known to be inhibited by fatty acid derivatives and obesity is strongly associated with elevated circulating fatty acids, we next tested the role of the fatty acid translocase CD36 in mediating VAT-induced Kir2.1 dysfunction. We found that the downregulation of CD36 restored Kir2.1 currents in endothelial cells exposed to VAT from obese mice. In addition, endothelial cells exposed to VAT from obese mice exhibited a significant increase in CD36-mediated fatty acid uptake. The importance of CD36 in obesity-induced endothelial dysfunction of VAT arteries was further supported in ex vivo pressure myography studies where CD36 ablation rescued the endothelium-dependent response to flow via restoring Kir2.1 and endothelial nitric oxide synthase function. These findings provide new insight into the role of VAT in mediating obesity-induced endothelial dysfunction and suggest a novel role for CD36 as a mediator of endothelial Kir2.1 impairment.NEW & NOTEWORTHY Our findings suggest a role for visceral adipose tissue (VAT) in the dysfunction of endothelial Kir2.1 in obesity. We further reveal a role for CD36 as a major contributor to VAT-mediated Kir2.1 and endothelial dysfunction, suggesting that CD36 offers a potential target for preventing the early development of obesity-associated cardiovascular disease.

Sodium valproate treatment reverses endothelial dysfunction in aorta from rabbits with acute myocardial infarction

Sodium valproate (VPA), a histone deacetylase (HDAC) inhibitor, could be a promising candidate to treat acute myocardial infarction (AMI). In this study, AMI was induced in New Zealand White rabbits by occluding the left circumflex coronary artery for 1 h, followed by reperfusion. The animals were distributed into three experimental groups: the sham-operated group (SHAM), the AMI group and the AMI + VPA group (AMI treated with VPA 500 mg/kg/day). After 5 weeks, abdominal aorta was removed and used for isometric recording of tension in organ baths or protein expression by Western blot, and plasma for the determination of nitrate/nitrite (NOx) levels by colorimetric assay. Our results indicated that AMI induced a reduction of the endothelium-dependent response to acetylcholine without modifying the endothelium-independent response to sodium nitroprusside, leading to endothelial dysfunction. VPA treatment reversed AMI-induced endothelial dysfunction and even increased NO sensitivity in vascular smooth muscle. This response was consistent with an antioxidant effect of VPA, as it was able to reverse the superoxide dismutase 1 (SOD 1) down-regulation induced by AMI. Our experiments also ruled out that the VPA mechanism was related to eNOS, iNOS, sGC and arginase expression or changes in NOx plasma levels. Therefore, we conclude that VPA improves vasodilation by increasing NO bioavailability, likely due to its antioxidant effect. Since endothelial dysfunction was closely related to AMI, VPA treatment could increase aortic blood flow, making it a potential agent in reperfusion therapy that can prevent the vascular damage.

Enhanced Microvascular Adaptation to Acute Physical Stress and Reduced Oxidative Stress in Male Athletes Who Consumed Chicken Eggs Enriched with n-3 Polyunsaturated Fatty Acids and Antioxidants-Randomized Clinical Trial.

This randomized interventional study aimed to determine the effects of n-3 polyunsaturated fatty acids, selenium, vitamin E, and lutein supplementation in the form of enriched chicken egg consumption on microvascular endothelium-dependent vasodilation, oxidative stress, and microvascular response to an acute strenuous training session (ASTS) in competitive athletes. Thirty-one male athletes were assigned to a control (n = 17) or a Nutri4 group (n = 14) who consumed three regular or enriched chicken eggs per day, respectively, for 3 weeks. Significantly enhanced endothelium-dependent responses to vascular occlusion (PORH) and iontophoresis of acetylcholine (AChID) were observed in the Nutri4 group but not in the control group after egg consumption. Formation of peroxynitrite and hydrogen peroxide in peripheral blood mononuclear cells, as well as serum concentration of 8-iso prostaglandin F2α, decreased in the Nutri4 group while remaining unchanged in controls. PORH and AChID were reduced post-ASTS compared with pre-ASTS, both before and after the diets, in both groups. However, the range of PORH responsiveness to ASTS (ΔPORH) increased after consumption of enriched eggs. These results suggest that consumption of enriched chicken eggs has a beneficial effect on microvascular endothelium-dependent vasodilation and the reduction of oxidative stress levels in competitive athletes. Also, microvascular adaptation to the ASTS was improved after consumption of Nutri4 eggs.

In vitro effect of relaxin in the rat corpus cavernosum under hyperglycemic and normoglycemic conditions.

Relaxin, an endogenous peptide hormone, elicits vascular relaxation by its direct effect or by modulating the endothelium-dependent relaxation response and is clinically evaluated for the treatment of coronary artery disease. However, its effect on penile tissue has not been explored yet. This study aimed to investigate the effect of serelaxin, recombinant human relaxin-2, on rat corpus cavernosum (CC) under healthy and hyperglycemic conditions. Strips of CC obtained from thirty-nine male Wistar rats weighing 300-350 g were used in organ baths for isometric tension studies to investigate the serelaxin-mediated relaxation (10-12-10-7 M) under normoglycemic conditions and the effect of serelaxin on endothelium-dependent [nitric oxide (NO)- and prostacyclin-mediated] relaxation responses under hyperglycemic conditions. The in vitro hyperglycemia model was created by 3 h of incubation with 44 mM glucose monohydrate +120 μM methylglyoxal. NO-dependent relaxation responses were evaluated by cumulative acetylcholine (10-9-10-4 M) administration in the presence of indomethacin (10-6 M). Prostacyclin-mediated relaxation was evaluated by cumulative administration of iloprost (10-9-10-6 M), a prostacyclin analog. Maximum relaxation responses to serelaxin were not significantly different compared to the time-control (p = 0.480). Three hours of incubation of rat CC in hyperglycemic conditions impaired NO- and prostacyclin-mediated relaxation responses (p = 0.032 and p = 0.047, respectively). Serelaxin coincubation worsened NO-mediated relaxation responses (p = 0.016) but did not affect prostacyclin-mediated responses (p = 0.425). Together, our results demonstrate that in vitro administration of serelaxin does not cause relaxation in penile tissue and short-term in vitro serelaxin treatment in hyperglycemic conditions mimicked diabetes modulates endothelium-dependent responses by worsening NO-mediated responses. Serelaxin exerts different effects via different mechanism on endothelium-dependent responses depending on the dose and duration of exposure. Therefore, proper timing and dosing of serelaxin administration in the penile tissue need to be investigated in further studies in diabetic animal models.

Effect of Nonsteroidal Mineralocorticoid Receptor Blocker Esaxerenone on Vasoreactivity to an Endothelial Stimulator in Superior Mesenteric Arteries of Type 2 Diabetic Goto-Kakizaki Rat.

Endothelial dysfunction contributes to cardiometabolic disorders, including hypertension, obesity, and type 2 diabetes. Esaxerenone is a selective, nonsteroidal, high-affinity mineralocorticoid receptor blocker recently approved in Japan for the treatment of hypertension. Although imbalanced signaling between vasorelaxant and vasocontractile factors induced by endothelial stimulation is often observed in type 2 diabetic vessels, the effects of esaxerenone on endothelium-dependent responses in type 2 diabetes remain unclear. The aim of this study was to investigate the effect of esaxerenone on endothelium-dependent responses in superior mesenteric arteries isolated from type 2 diabetic Goto-Kakizaki (GK) rats. It was found that esaxerenone (3 mg/kg/d for 4 weeks, per os (p.o.)) partially ameliorated acetylcholine (ACh)-induced endothelium-derived hyperpolarizing factor (EDHF)-type relaxation and NS309, a potent activator of small- and intermediate-conductance Ca2+-activated K+ channels, -induced relaxation, and reduced ACh-induced endothelium-derived contracting factor (EDCF)-mediated contraction. These results suggest that esaxerenone ameliorates endothelial function through increased EDHF signaling and suppressed EDCF signaling.

Treatment with Resveratrol Reverses Priapism in the Sickle Cell Mouse

Introduction: Sickle cell disease (SCD) men display priapism. Townes and Berkeley SCD mice models are widely studied in basic sciences because they express 100% HbS in their circulating erythrocytes and exhibit features of priapism, and, as in SCD humans, this appears to be due to decreased nitric oxide (NO) signaling and increased oxidative stress, which leads to lower PDE5 in the penis. Thus, when an erectile stimulus occurs in vivo, cGMP accumulates into the cavernosal smooth muscle cells, rendering the penile vasculature uncontrollably dilated, and penile erection persists (i.e., priapism) as cGMP is not degraded as a consequence of PDE5 downregulation. Moreover, oxidative/nitrosative stress has been associated with priapism in SCD mice.Resveratrol (trans-3,5,4′-trihydroxystilbene) is a natural phytoalexin product with potent antioxidant activity found in peanuts, berries, and grapes. In this study, since decreased NO bioavailability and increased oxidative stress leads to lower PDE5 in the penis, we aimed to evaluate the effects of resveratrol on functional and molecular alterations of erectile function in SCD mice. We have focused on the dysregulated NO-cGMP-PDE5 pathway and oxidative/nitrosative stress markers (4-HNE and 3-nitrotyrosine) in the erectile tissue of SCD. Methods: Wild type (WT, C57BL/6) and Townes SCD transgenic male mice (3-5 mo old) were treated with resveratrol (100 mg /kg/day) or its vehicle daily for two weeks via gavage. Corpus cavernosum (CC) strips were mounted in isolated organ baths, and the relaxing responses to acetylcholine (ACh; endothelium-dependent response) and sodium nitroprusside (SNP; endothelium-independent response), as well as electrical-field stimulation (EFS; nitrergic relaxation), were obtained in CC strips precontracted with the α1-adrenergic receptor agonist phenylephrine (3-10 µM). Results: The cumulative addition of ACh (0.001-10 µM) produced concentration-dependent CC relaxations in WT and SCD groups, but the ACh potency (pEC50) value was higher (P<0.05) in CC of SCD compared to WT mice, which was reversed by resveratrol. Likewise, the nitrergic relaxation induced by EFS was also higher (P<0.05) in SCD mice compared to control mice (4 Hz: 30 ± 8 and 80 ± 5 %, respectively; n=5), which was reversed by resveratrol treatment. Similarly, SNP (0.01- 10 µM) produced concentration-dependent CC relaxations in WT and SCD groups, but, again, the maximal relaxations elicited by this agent were higher (P<0.05) in SCD (90 ± 1%) group compared to the WT mice (65 ± 6%), which were fully restored to WT values with resveratrol treatment (n=6). The mRNA expression for the PDE5 was reduced (P<0.05) by approximately 57% in penile tissues from SCD compared to the WT group, respectively. Resveratrol treatment restored (P<0.05) the mRNA expression of PDE5 in the penises from the SCD group (n=5-6). The protein expressions for 4-HNE and 3-nitrotyrosine (3-NT) were significantly higher (P<0.05) in erectile tissues from SCD compared to the WT group, which were reduced (P<0.05) by resveratrol treatment (n=6). In WT mice, PDE5, 4-HNE, and 3-NT protein expressions were not affected by resveratrol, as well as CC relaxations induced by ACh, SNP, and EFS. Conclusion: Resveratrol treatment reduced enhanced NO-mediated CC relaxations along with normalization of PDE5 expression and reduced oxidative stress markers expressions (3-NT and 4-HNE) in the penises from SCD. Therefore, resveratrol may constitute an additional strategy to prevent priapism in SCD. Financial Support: FAPESP.

Wax apple (Syzygiumsamarangense) fruit extract ameliorates endothelial dysfunction and liver damage in high cholesterol diet-fed rats

Background and aimWax apple fruit (Syzygium samarangense) is one of the most popular tropical fruit in Asia, and contains several essential nutrients. Therefore, this study explored the effects of the wax apple fruit extract on a high-cholesterol diet-induced vascular endothelial dysfunction and fatty liver in rats. Experimental procedureMale Sprague Dawley rats were fed a diet with 1.5% cholesterol (HCD) for 8 weeks, and were given wax apple fruit extract (50 and 100 mg/kg/day) orally for the last 4 weeks. After 8 weeks, blood sample, thoracic aorta, and liver were collected and processed for biochemical and histological analysis. Additionally, vascular endothelial function and the protein expression of oxidative stress markers in aortae were evaluated. Results and conclusionWax apple reduced serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), but increased high-density lipoprotein cholesterol (HDL-C) levels. Furthermore, the liver levels of TG and TC were reduced in wax apple-treated hypercholesterolemic rats. Histological studies revealed that wax apple ameliorated HCD-induced morphologic changes of aortic and liver tissues of rats. In aortic tissues, the impaired endothelium-dependent responses to acetylcholine, the reduced nitric oxide (NO) contents, the elevated endothelin (ET)-1 contents, and the increased expression of NADPH oxidase subunit p47phox and 4-hydroxynonenal in HCD-fed rats were reversed by wax apple treatment. These results suggest that oral administration of wax apple improves vascular dysfunction and damage in hypercholesterolemic rats possibly through increasing NO bioavailability, decreasing ET-1 levels and reducing oxidative stress. Furthermore, wax apple ameliorates the HCD-induced fatty liver in rats.

Effects of dietary palmitoleic acid on vascular function in aorta of diabetic mice

BackgroundChronic hyperglycemia in diabetes causes atherosclerosis and progresses to diabetic macroangiopathy, and can lead to coronary heart disease, myocardial infarction and cerebrovascular disease. Palmitoleic acid (POA) is a product of endogenous lipogenesis and is present in fish and vegetable oil. In human and animal studies, POA is reported as a beneficial fatty acid related to insulin sensitivity and glucose tolerance. However, few studies have reported its effects on aortic function in diabetes. Here, we investigated the effects of POA administration on vascular function in KKAy mice, a model of type 2 diabetes.MethodsMale C57BL/6 J (control) and KKAy (experimental) mice at the age of 14 weeks were used in the present study. For each mouse strain, one group was fed with reference diet and a second group was fed POA-containing diet for 2 weeks. The vascular reactivities of prepared aortic rings were then measured in an organ bath to determine if POA administration changed vascular function in these mice.ResultsKKAy mice treated with POA exhibited decreased plasma glucose levels compared with mice treated with reference diet. However, endothelium-dependent vasorelaxant responses to acetylcholine and protease-activated receptor 2 activating protein, which are attenuated in the aorta of KKAy mice compared to C57BL/6 J mice under a reference diet, were not affected by a 2-week POA treatment. In addition, assessment of vasoconstriction revealed that the phenylephrine-induced vasoconstrictive response was enhanced in KKAy mice compared to C57BL/6 J mice under a reference diet, but no effect was observed in KKAy mice fed a POA-containing diet. In contrast, there was an increase in vasoconstriction in C57BL/6 J mice fed the POA-containing diet compared to mice fed a reference diet. Furthermore, the vasoconstriction in aorta in both C57BL/6 J and KKAy mice fed a POA-containing diet were further enhanced under hyperglycemic conditions compared to normal glucose conditions in vitro. In the hyperinsulinemic, and hyperinsulinemic combined with hyperglycemic conditions, vasoconstriction was increased in KKAy mice fed with POA.ConclusionThese results suggest that POA intake enhances vasoconstriction under hyperglycemic and hyperinsulinemic conditions, which are characteristics of type 2 diabetes, and may contribute to increased vascular complications in diabetes.

Characterization of hypotensive and vasorelaxant effects of PHAR-DBH-Me a new cannabinoid receptor agonist.

The effect of PHAR-DBH-Me, a cannabinoid receptor agonist, on different cardiovascular responses in adult male rats was analyzed. The blood pressure was measured directly and indirectly. The coronary flow was measured by Langendorff preparation, and vasomotor responses induced by PHAR-DBH-Me in aortic rings pre-contracted with phenylephrine (PHEN) were analyzed. The intravenous injection of the compound PHAR-DBH-Me (0.018–185 µg/kg) resulted in decreased blood pressure; maximum effect was observed at the dose of 1,850 µg/kg. A concentration-dependent increase in the coronary flow was observed in a Langendorff preparation. In the aortic rings, with and without endothelium, pre-contracted with PHEN (10–6 M), the addition of PHAR-DBH-Me to the superfusion solution (10–12–10–5 M), produced a vasodilator response, which depends on the concentration and presence of the endothelium. L-NAME inhibited these effects. Addition of CB1 receptor antagonist (AM 251) did not modify the response, while CB2 receptor antagonist (AM630) decreased the potency of relaxation elicited by PHAR-DBH-Me. Indomethacin shifted the curve concentration-response to the left and produced an increase in the magnitude of the maximum endothelium dependent response to this compound. The maximum effect of PHAR-DBH-Me was observed with the concentration of 10–5 M. These results show that PHAR-DBH-Me has a concentration-dependent and endothelium-dependent vasodilator effect through CB2 receptor. This vasodilation is probably mediated by the synthesis/release of NO. On the other hand, it is suggested that PHAR-DBH-Me also induces the release of a vasoconstrictor prostanoid.

Endothelial-Dependent Responses Correlate with Pediatric SOFA Scores During Severe Sepsis and Septic Shock.

Sepsis is an exaggerated host response to an infectious challenge that is associated with significant alterations in vasomotor tone. We hypothesized that the endothelial dysfunction observed during severe sepsis and septic shock would correlate with the degree of organ failure as determined by the pediatric Sequential Organ Failure Assessment (pSOFA) score. Utilizing laser Doppler perfusion monitoring coupled with iontophoresis, we found that endothelium-dependent vascular reactivity to acetylcholine (ACh) stimulation significantly correlated with both total pSOFA scores and, more specifically, cardiovascular (CV) pSOFA scores. Alternatively, endothelium-independent vascular reactivity using sodium nitroprusside (SNP) did not demonstrate a significant relationship with pSOFA scores. These data suggest that endothelial-mediated vasculopathy may be a key driver of organ dysfunction during episodes of pediatric sepsis.

Role of heme oxygenase in the regulation of the renal hemodynamics in a model of sex-dependent programmed hypertension by maternal diabetes.

Intrauterine programming of cardiovascular and renal function occurs in diabetes because of the adverse maternal environment. Heme oxygenase 1 (HO-1) and -2 (HO-2) exert vasodilatory and antioxidant actions, particularly in conditions of elevated HO-1 expression or deficient nitric oxide levels. We evaluated whether the activity of the heme-HO system is differentially regulated by oxidative stress in the female offspring of diabetic mothers, contributing to the improved cardiovascular function in comparison with males. Diabetes was induced in pregnant rats by a single dose of streptozotocin (STZ, 50 mg/kg ip) in late gestation. Three-month-old male offspring from diabetic mothers (MODs) exhibited higher blood pressure (BP), higher renal vascular resistance (RVR), worse endothelium-dependent response to acetylcholine (ACH), and an increased constrictor response to phenylephrine (PHE) compared with those in age-matched female offspring of diabetic mothers (FODs), which were abolished by chronic tempol (1 mM) treatment. In anesthetized animals, stannous mesoporphyrin (SnMP; 40 µmol/kg iv) administration, to inhibit HO activity, increased RVR in FODs and reduced glomerular filtration rate (GFR) in MODs, without altering these parameters in control animals. When compared with MODs, FODs showed lower nitrotirosyne levels and higher HO-1 protein expression in renal homogenates. Indeed, chronic treatment with tempol in MODs prevented elevations in nitrotyrosine levels and the acute renal hemodynamics response to SnMP. Then, maternal diabetes results in sex-specific hypertension and renal alterations associated with oxidative stress mainly in adult male offspring, which are reduced in the female offspring by elevation in HO-1 expression and lower oxidative stress levels.

Preservation of Adrenoceptor and Endothelin Receptor Mediated Vasoconstriction and of Endothelium-Dependent Relaxation after Cold Storage of Explanted Blood Vessels for ex vivo Analyses.

Adrenoceptor and endothelin (ET) receptor-mediated vasoconstriction as well as endothelium-dependent vasodilation of human saphenous veins were compared before and after 20 h of cold storage. Contractile responses to potassium chloride (KCl), norepinephrine (NE), and ET-1 as well as vasodilator responses to acetylcholine (ACh) were evaluated. Storage in HEPES-supplemented Dulbecco's modified Eagle's medium (HDMEM) diminished KCl induced contractile forces to 71% (p = 0.002) and NE induced contractions to 80% (p = 0.037), in contrast to HEPES-supplemented Krebs-Henseleit solution (HKH) and TiProtec solution. KCl-normalized NE contractions were not affected by storage. NE EC50 values were slightly lower (7.1E-8 vs. 7.5E-8, p = 0.019) after storage in HKH, with no changes after storage in the other solutions. Endothelium-dependent responses to ACh were not affected by storage. ET-1 induced contractions were attenuated after storage in HDMEM (77%, p = 0.002), HKH (75%, p = 0.020), and TiProtec (73%, p = 0.010) with no changes in normalized constrictions. ET-1 EC50 values were not affected by storage. Loss of contractility after storage in HDMEM may reflect the lower content of dextrose. There was no specific attenuation of adrenoceptor, ET-receptor, or ACh receptor mediated signal transduction after storage in any of the media. HKH or TiProtec are equally suitable cold storage solutions for ex vivo measurements.

Does the Endothelium of Competitive Athletes Benefit from Consumption of n-3 Polyunsaturated Fatty Acid-Enriched Hen Eggs?

The present study aimed to determine the effect of n-3 polyunsaturated fatty acid (PUFA)-enriched hen eggs on microvascular vasodilation, microvascular responsiveness to a stress challenge and markers of oxidative stress in competitive athletes. Competitive athletes (n=23) were divided to a control group (n=9), who consumed three regular hens’ eggs daily (249 mg n-3 PUFAs/d), and n-3 PUFAs group (n=14), who consumed three n-3 PUFA-enriched hen eggs daily (1,053 g n-3 PUFAs/d) for 3 weeks. Endothelium-dependent responses [post-occlusive reactive hyperemia (PORH) and acetylcholine-induced dilation (AChID)] and endothelium-independent responses [sodium nitroprusside-induced dilation (SNPID)] of skin microvascular blood flow were assessed by laser Doppler flowmetry in pre- and post-acute exhausting exercise (AEE) sessions. Blood pressure, serum lipid, free fatty acids profiles, and biomarkers of oxidative stress were measured before and after each dietary protocol. Consumption of serum n-3 PUFAs significantly decreased the n-6/n-3 ratio and enhanced PORH and AChID, but did not affect SNPID at rest. Furthermore, serum glutathione peroxidase and superoxide dismutase activities were significantly decreased in the n-3 PUFAs group but remained unchanged in the control group. In both groups, PORH, AChID, and SNP were significantly reduced post-AEE compared with pre-AEE, both before and after consumption of each diet. Only AChID responsiveness to AEE (ΔAChID) significantly increased following consumption of n-3 PUFAs. Overall, n-3 PUFAs supplementation as n-3 PUFA-enriched hen eggs enhanced microvascular endothelial function at rest and may contribute to adaptation to AEE in competitive athletes.

High Soluble Endoglin Levels Affect Aortic Vascular Function during Mice Aging.

Endoglin is a 180 kDa transmembrane glycoprotein that was demonstrated to be present in two different endoglin forms, namely membrane endoglin (Eng) and soluble endoglin (sEng). Increased sEng levels in the circulation have been detected in atherosclerosis, arterial hypertension, and type II diabetes mellitus. Moreover, sEng was shown to aggravate endothelial dysfunction when combined with a high-fat diet, suggesting it might be a risk factor for the development of endothelial dysfunction in combination with other risk factors. Therefore, this study hypothesized that high sEng levels exposure for 12 months combined with aging (an essential risk factor of atherosclerosis development) would aggravate vascular function in mouse aorta. Male transgenic mice with high levels of human sEng in plasma (Sol-Eng+) and their age-matched male transgenic littermates that do not develop high soluble endoglin (Control) on a chow diet were used. The aging process was initiated to contribute to endothelial dysfunction/atherosclerosis development, and it lasted 12 months. Wire myograph analysis showed impairment contractility in the Sol-Eng+ group when compared to the control group after KCl and PGF2α administration. Endothelium-dependent responsiveness to Ach was not significantly different between these groups. Western blot analysis revealed significantly decreased protein expression of Eng, p-eNOS, and ID1 expression in the Sol-Eng+ group compared to the control group suggesting reduced Eng signaling. In conclusion, we demonstrated for the first time that long-term exposure to high levels of sEng during aging results in alteration of vasoconstriction properties of the aorta, reduced eNOS phosphorylation, decreased Eng expression, and altered Eng signaling. These findings suggest that sEng can be considered a risk factor for the development of vascular dysfunction during aging and a potential therapeutical target for pharmacological intervention.

Abstract 9356: The Effect of Intraoperative Oxygenation on Vascular Reactivity in Human Resistance Arterioles

Introduction: Hyperoxia during surgery is common and may promote oxidative stress. Oxidative stress uncouples endothelial nitric oxide synthase and may impair vascular reactivity, a key regulator of tissue perfusion. Hypothesis: Hyperoxia during cardiac surgery impairs vascular reactivity compared to normoxia. Methods: We isolated resistance-level arterioles from mediastinal fat collected from subjects in a clinical trial of hyperoxia versus normoxia during cardiac surgery. Tissue was obtained at the end of surgery, and arterioles from 24 subjects were mounted on a wire myograph. After norepinephrine contraction, we measured the endothelium-dependent response to acetylcholine and the endothelium-independent response to sodium nitroprusside. To further identify if hyperoxygenation impairs nitric oxide mediated vasodilation via oxidation of the soluble guanylyl cyclase heme moiety, we measured the response to the heme-independent soluble guanylyl cyclase activator cinaciguat. We compared relaxation to increasing doses of each vasodilator in normoxia vs. hyperoxia treated arterioles using repeated measures ANOVA and nonlinear mixed effects regression. Results: The acetylcholine response was uniformly impaired (P=0.98, Figure ). The sodium nitroprusside response was selectively impaired in hyperoxia treatment vs. normoxia as reflected by a higher EC50 (EC50: 50.1±6.3 x10-8 M for hyperoxia vs. 7.9 ± 0.8 x 10-8 M for normoxia, P=0.02) and decreased peak response. In striking contrast to the response to sodium nitroprusside, vasodilation evoked by cinaciguat was not impaired and was slightly enhanced for hyperoxia vs. normoxia (EC50: 7.9±0.8 x10-8 M vs. 15.8±6.2 x10-8 M; P=0.07, Figure). Conclusions: Intraoperative hyperoxia impaired human arteriole vasodilation likely via oxidation of the soluble guanylyl cyclase heme moiety. These data provide additional mechanistic insight into potential harmful effects of intraoperative hyperoxia.