Lack of synergistic interaction between quercetin and catechin in systemic and pulmonary vascular smooth muscle

Due to their ubiquitous distribution, flavonoids from different classes are commonly present together in foods. However, little is known about the interactions between them. The flavonol quercetin and the flavan-3-ol (+)-catechin are among the most abundant flavonoids in the diet. In the present study, we have analysed the interactions between these two flavonoids on vascular function using two pure compounds and mixtures of these flavonoids in 1:0·1, 1:1 or 1:10 proportions. Quercetin induced a more potent concentration-dependent relaxant effect than catechin in the isolated rat aorta, and the isobolographic analysis of the mixtures showed no synergistic or antagonistic effects between them, i.e. their effects were additive. Quercetin was more potent in mesenteric than in pulmonary arteries. Catechin had weak effects in these vessels and did not modify the effects of quercetin. Endothelial dysfunction induced by increased oxidative stress by the superoxide dismutase inhibitor diethyldithiocarbamate was prevented by quercetin, whereas catechin showed a weak effect and the 1:1 mixture an intermediate effect compared with the pure compounds. Quercetin but not catechin showed a pro-oxidant and NO-scavenging effect, which was not prevented by catechin. In conclusion, catechin was less potent than quercetin as a vasodilator, pro-oxidant or to prevent endothelial dysfunction, and there were no synergistic interactions between quercetin and catechin.

Download Full-text

Persistence of EDHF pathway and impairment of the nitric oxide pathway after chronic mercury chloride exposure in rats: Mechanisms of endothelial dysfunction

Human & Experimental Toxicology ◽

10.1177/0960327110391389 ◽

2010 ◽

Vol 30 (11) ◽

pp. 1777-1784 ◽

Cited By ~ 12

Author(s):

S Omanwar ◽

K Ravi ◽

M Fahim

Keyword(s):

Nitric Oxide ◽

Endothelial Dysfunction ◽

Vascular Function ◽

Rat Aorta ◽

Mercury Exposure ◽

Mercury Chloride ◽

Dependent Manner ◽

Selective Loss ◽

Dose Dependent ◽

Endothelium Dependent Relaxation

Chronic mercury exposure impairs vascular function, leading to the depression of endothelium-dependent vasodilatation. Loss of the nitric oxide (NO) pathway has been implicated, but little is known about effects on other endothelial mediators. This study investigated the mechanisms of endothelial dysfunction in rats subjected to chronic mercury chloride exposure. The endothelium-dependent relaxation of rat aorta evoked by acetylcholine (ACh) and isoproterenol was impaired in a dose-dependent manner by chronic mercury chloride exposure. Endothelium-independent responses to sodium nitroprusside (SNP) were not affected by chronic mercury chloride exposure. In healthy vessels, ACh-induced relaxation was inhibited by L-N-nitroarginine methyl ester (L-NAME; 10–4M) and partially by glybenclamide (10–5M), indicating the involvement of NO and endothelium-derived hyperpolarizing factor (EDHF). In vessels from mercury-exposed rats, responses to ACh were insensitive to L-NAME but were significantly reduced by glybenclamide, indicating selective loss of NO-mediated relaxation. In vessels from mercury-exposed rats, responses to ACh were partially restored after treatment with the antioxidant, superoxide dismutase (SOD) and catalase, this effect was not seen when aorta from exposed group was incubated with L-NAME along with SOD and catalase indicating selective loss of NO-mediated vasodilatation and with no affect the EDHF-mediated component of relaxation. The results imply that chronic mercury exposure selectively impairs the NO pathway as a consequence of oxidative stress, while EDHF is able to maintain endothelium-dependent relaxation at a reduced level.

Download Full-text

Acidic reoxygenation protects against endothelial dysfunction in rat aortic rings submitted to simulated ischemia

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00409.2008 ◽

2008 ◽

Vol 295 (6) ◽

pp. H2409-H2416 ◽

Cited By ~ 11

Author(s):

Diego López ◽

Antonio Rodríguez-Sinovas ◽

Luis Agulló ◽

Javier Inserte ◽

Alberto Cabestrero ◽

...

Keyword(s):

Endothelial Dysfunction ◽

Sodium Nitroprusside ◽

Vascular Function ◽

Ischemia Reperfusion ◽

Rat Aorta ◽

Functional Improvement ◽

Sprague Dawley ◽

Response Curves ◽

Simulated Ischemia ◽

Cgmp Signaling

Ischemia-reperfusion causes endothelial dysfunction. Prolongation of acidosis during initial cardiac reperfusion limits infarct size in animal models, but the effects of acidic reperfusion on vascular function are unknown. The present work analyzes the effects of acidic reoxygenation on vascular responses to different agonists in rat aortic rings. Arterial rings obtained from Sprague-Dawley rat aorta were placed in organ baths containing a Krebs solution oxygenated at 37°C (pH 7.4). After equilibration (30 mN, 1 h), the effects of acidosis (pH 6.4) on aortic responses to acetylcholine and norepinephrine were initially assessed under normoxic conditions. Thereafter, the effects of acidosis during hypoxia (1 h) or reoxygenation on aortic responses to acetylcholine, norepinephrine, or sodium nitroprusside were analyzed and compared with those observed in control rings. Acidosis did not modify aortic responses to acetylcholine or adrenaline during normoxia. In contrast, rings submitted to hypoxia and reoxygenated at pH 7.4 showed a reduction in vasodilator responses to acetylcholine and in contractions to norepinephrine with no change in responses to sodium nitroprusside. Reoxygenation at pH 6.4 did not modify the depressed response to norepinephrine but enhanced the recovery of acetylcholine-induced vasorelaxation. Cumulative concentration-response curves to acetylcholine showed an increased responsiveness to this drug in rings reoxygenated at a low pH. This functional improvement was associated with the preservation of aortic cGMP content after stimulation of reoxygenated rings with acetylcholine. In conclusion, acidic reoxygenation preserves endothelial function in arterial rings submitted to simulated ischemia, likely through the preservation of cGMP signaling.

Download Full-text

Preferential Vasodilator Effects of Levosimendan in Resistance Pulmonary Arteries in a Rodent Pulmonary Embolism Model

International Cardiovascular Forum Journal ◽

10.17987/icfj.v11i0.433 ◽

2017 ◽

Vol 11 ◽

Cited By ~ 1

Author(s):

Camila Bedo ◽

Juan C Grignola

Keyword(s):

Pulmonary Embolism ◽

Vascular Function ◽

Wistar Rats ◽

Saline Solution ◽

Acute Hypoxia ◽

Pulmonary Arteries ◽

Mesenteric Arteries ◽

Response Curves ◽

Relaxant Effect ◽

Male Wistar Rats

Background: We compared the vasoactive effects of levosimendan on isolated conduit (CPA) and resistance (RPA) pulmonary arteries versus mesenteric arteries and we assessed the PA vascular function and the PA vasoactive effects of levosimendan in a rodent PE model.Methods: One group of male Wistar rats (200-300 g) was killed by decapitation to obtain pulmonary and mesenteric rings. Another group was assigned to a massive PE or saline solution infusion. After euthanasia mesenteric arteries and CPA (i.d. 1-2 mm) and RPA (≤ 0.5 mm) were dissected and cut into 2-3 mm wide rings recording contractile tension. We obtained the concentration-response curves of cumulative doses of levosimendan on pre-contracted arterial rings from decapitated and sham/embolized animals. A set of RPA rings was exposed to acute hypoxia. The effect of PE on the pulmonary vasoactive function was assessed by dose-response curves of acetylcholine (ACh) and endothelin-1 (ET-1) of PA rings from sham/embolized animals. Results: Levosimendan relaxant potency of RPA was similar to mesenteric arteries and higher than CPA, while mesenteric rings showed the maximal relaxant effect, followed by RPA and CPA, respectively. PE did not affect the vasoactive response of PA rings either to ACh or to ET-1, and the relaxant effects of CPA and RPA to levosimendan were also preserved. Acute hypoxia reduced (P<0.05) but did not avoid the RPA relaxant effect of levosimendan.Conclusions: Levosimendan is a more specific vasodilator of RPA with a similar relaxant potency as mesenteric arteries, which is preserved after PE but significantly reduced during hypoxia.

Download Full-text

The Sodium-Glucose Cotransporter-2 Inhibitor Canagliflozin Alleviates Endothelial Dysfunction Following In Vitro Vascular Ischemia/Reperfusion Injury in Rats

International Journal of Molecular Sciences ◽

10.3390/ijms22157774 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7774

Author(s):

Sevil Korkmaz-Icöz ◽

Cenk Kocer ◽

Alex A. Sayour ◽

Patricia Kraft ◽

Mona I. Benker ◽

...

Keyword(s):

Endothelial Dysfunction ◽

Reperfusion Injury ◽

Vascular Function ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Artery Bypass ◽

Diabetic Rats ◽

Organ Bath ◽

Sodium Glucose Cotransporter

Vascular ischemia/reperfusion injury (IRI) contributes to graft failure and adverse clinical outcomes following coronary artery bypass grafting. Sodium-glucose-cotransporter (SGLT)-2-inhibitors have been shown to protect against myocardial IRI, irrespective of diabetes. We hypothesized that adding canagliflozin (CANA) (an SGLT-2-inhibitor) to saline protects vascular grafts from IRI. Aortic rings from non-diabetic rats were isolated and immediately mounted in organ bath chambers (control, n = 9–10 rats) or underwent cold ischemic preservation in saline, supplemented either with a DMSO vehicle (IR, n = 8–10 rats) or 50µM CANA (IR + CANA, n = 9–11 rats). Vascular function was measured, the expression of 88 genes using PCR-array was analyzed, and feature selection using machine learning was applied. Impaired maximal vasorelaxation to acetylcholine in the IR-group compared to controls was significantly ameliorated by CANA (IR 31.7 ± 3.2% vs. IR + CANA 51.9 ± 2.5%, p < 0.05). IR altered the expression of 17 genes. Ccl2, Ccl3, Ccl4, CxCr4, Fos, Icam1, Il10, Il1a and Il1b have been found to have the highest interaction. Compared to controls, IR significantly upregulated the mRNA expressions of Il1a and Il6, which were reduced by 1.5- and 1.75-fold with CANA, respectively. CANA significantly prevented the upregulation of Cd40, downregulated NoxO1 gene expression, decreased ICAM-1 and nitrotyrosine, and increased PECAM-1 immunoreactivity. CANA alleviates endothelial dysfunction following IRI.

Download Full-text

Endothelial dysfunction and body mass index: is there a role for plasma peroxynitrite?

Beni-Suef University Journal of Basic and Applied Sciences ◽

10.1186/s43088-020-00092-6 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Theresa Chikopela ◽

Douglas C. Heimburger ◽

Longa Kaluba ◽

Pharaoh Hamambulu ◽

Newton Simfukwe ◽

...

Keyword(s):

Oxidative Stress ◽

Nitric Oxide ◽

Endothelial Dysfunction ◽

Body Mass ◽

Vascular Function ◽

Aortic Ring ◽

Normal Weight ◽

Oxide Synthase ◽

Weight Groups

Abstract Background Endothelial function is dependent on the balance between vasoconstrictive and vasodilatory substances. The endothelium ability to produce nitric oxide is one of the most crucial mechanisms in regulating vascular tone. An increase in inducible nitric oxide synthase contributes to endothelial dysfunction in overweight persons, while oxidative stress contributes to the conversion of nitric oxide to peroxynitrite (measured as nitrotyrosine in vivo) in underweight persons. The objective of this study was to elucidate the interaction of body composition and oxidative stress on vascular function and peroxynitrite. This was done through an experimental design with three weight groups (underweight, normal weight and overweight), with four treatment arms in each. Plasma nitrotyrosine levels were measured 15–20 h post lipopolysaccharide (LPS) treatment, as were aortic ring tension changes. Acetylcholine (ACh) and sodium nitroprusside (SNP) challenges were used to observe endothelial-dependent and endothelial-independent vascular relaxation after pre-constriction of aortic rings with phenylephrine. Results Nitrotyrosine levels in saline-treated rats were similar among the weight groups. There was a significant increase in nitrotyrosine levels between saline-treated rats and those treated with the highest lipopolysaccharide doses in each of the weight groups. In response to ACh challenge, Rmax (percentage reduction in aortic tension) was lowest in overweight rats (112%). In response to SNP, there was an insignificantly lower Rmax in the underweight rats (106%) compared to the normal weight rats (112%). Overweight rats had a significant decrease in Rmax (83%) in response to SNP, signifying involvement of a more chronic process in tension reduction changes. A lower Rmax accompanied an increase in peroxynitrite after acetylcholine challenge in all weight groups. Conclusions Endothelial dysfunction, observed as an impairment in the ability to reduce tension, is associated with increased plasma peroxynitrite levels across the spectrum of body mass. In higher-BMI rats, an additional role is played by vascular smooth muscle in the causation of endothelial dysfunction.

Download Full-text

An anxiolytic drug buspirone ameliorates hyperglycemia and endothelial dysfunction in type 2 diabetic rat model

Turkish Journal of Biochemistry ◽

10.1515/tjb-2019-0224 ◽

2020 ◽

Vol 45 (4) ◽

pp. 397-404

Author(s):

Tugba Gurpinar Çavuşoğlu ◽

Ertan Darıverenli ◽

Kamil Vural ◽

Nuran Ekerbicer ◽

Cevval Ulman ◽

...

Keyword(s):

Type 2 Diabetes ◽

Blood Glucose ◽

Endothelial Dysfunction ◽

Vascular Function ◽

Fasting Blood Glucose ◽

Diabetic Rats ◽

Diabetic Rat ◽

Insulin Levels ◽

Type 2 Diabetic

AbstractObjectivesType 2 diabetes is a common metabolic disease and anxiety disorders are very common among diabetics. Buspirone is used in the treatment of anxiety, also having blood glucose-lowering effects. The aim of the study was to investigate the effects of buspirone on the glucose and lipid metabolism as well as vascular function in type 2 diabetic rats.MethodsA type 2-diabetic model was induced through a high-fat diet for eight weeks followed by the administration of low-dose streptozotocin (35 mg/kg, intraperitoneal) in rats. Buspirone was given at two different doses (1.5 mg/kg/d and 5 mg/kg/d) and combined with metformin (300 mg/kg/d). The fasting glucose and insulin levels, lipid profile were analyzed, and vascular response measured from the thoracic aorta was also evaluated.ResultsBoth doses of buspirone caused a significant improvement in fasting blood glucose levels. In particular, the buspirone treatment, combined with metformin, improved endothelial dysfunction and was found to be correlated with decreased nitrate/nitrite levels.ConclusionsBuspirone may be effective in the treatment of type 2 diabetes, either alone or in combination with other treatments, particularly in terms of endothelial dysfunction, inflammation and impaired blood glucose, and insulin levels.

Download Full-text

Abstract P347: Retinol-binding Protein 7 (RBP7) is Required for PPARG-mediated Endothelial Protection via Adiponectin

Hypertension ◽

10.1161/hyp.68.suppl_1.p347 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

Chunyan Hu ◽

Henry L Keen ◽

Ko-Ting Lu ◽

Deborah R Davis ◽

Xuebo Liu ◽

...

Keyword(s):

Endothelial Dysfunction ◽

Rna Sequencing ◽

Basilar Artery ◽

Vascular Function ◽

Carotid Arteries ◽

Target Genes ◽

Binding Protein ◽

Retinol Binding Protein ◽

Specific Expression ◽

Fatty Acid Binding

PPARγ protects against endothelial dysfunction by regulation of unknown target genes. One such target, RBP7, an intracellular fatty acid-binding protein, exhibits endothelium-specific expression, but its effect on vascular function remain unknown. We hypothesize that RBP7 is endothelial protective. We examined vascular responses in basilar artery (pressurized myograph) of RBP7-knockout (KO) and wild type (WT) mice fed normal chow (ND) or high fat diet (HFD) for 8 wks. Endothelium-dependent acetylcholine (ACh)-induced relaxation was significantly impaired in HFD-fed KO mice (ACh, 100μM: 33±7% KO vs 83±10% WT, p<0.05), but not in ND-fed groups. This response was ameliorated by pre-incubation with superoxide scavenger tempol (1mM) or PEG-superoxide dismutase (100 U/ml). Mean arterial pressure (measured by radiotelemetry), body weight, hepatic steatosis, fasting glucose, glucose tolerance, and insulin sensitivity were similar in HFD-fed KO and WT mice. To identify targets downstream of RBP7, RNA-Sequencing was performed on carotid arteries from 8-week HFD-fed WT and KO mice as well as ND-fed age-matched littermates. Adiponectin (AdipoQ), a PPARγ target, was increased ~6-fold in HFD-fed WT mice, a response that was markedly blunted in KO mice. RNA sequencing was confirmed by qPCR. There was no difference in plasma AdipoQ. AdipoQ protein is expressed in endothelial cells of carotid arteries and its level of expression was increased in HFD-fed WT but not KO mice (AdipoQ/CD31: 1.14±0.1 WT-HFD vs 0.82±0.1 WT-ND, p<0.05; 0.79±0.1 KO-HFD vs 0.81±0.04 KO-ND). This led us to hypothesize that AdipoQ is involved in RBP7-mediated endothelial protection. Incubation of basilar artery with mouse full-length AdipoQ protein (5 μg/mL, 4 hours) significantly ameliorated endothelial dysfunction (ACh, 100 μM: 56±6% AdipoQ+KO vs 26±3% KO, p<0.05) and blunted carotid artery superoxide production in HFD-fed KO mice. AdipoQ also protects against endothelial dysfunction caused by subpressor Ang-II in KO mice. We conclude that RBP7 protects the endothelium from oxidative stress-induced dysfunction through an AdipoQ-dependent mechanism. Our evidence suggests RBP7 is an essential cofactor for activation of some PPARγ target genes in the endothelium.

Download Full-text

MO1008IMPACT OF RAMIPRIL ON ENDOTHELIAL DYSFUNCTION IN CHILDREN ON REGULAR HEMODIALYSIS

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfab108.005 ◽

2021 ◽

Vol 36 (Supplement_1) ◽

Author(s):

Areej Mohamed Ateya ◽

Reinhold Kreutz ◽

Ihab Elhakim ◽

Sara Shaheen ◽

Radwa Maher ◽

...

Keyword(s):

Placebo Group ◽

Endothelial Dysfunction ◽

Serum Potassium ◽

Vascular Function ◽

Pediatric Patients ◽

Acute Infection ◽

Immunosuppressive Agents ◽

Maintenance Hemodialysis ◽

Short Term Treatment ◽

Regular Hemodialysis

Abstract Background and Aims Endothelial dysfunction is an important risk factor for cardiovascular disease and therefore for increased mortality in end-stage renal disease patients. Asymmetric dimethyl arginine (ADMA), a potent inhibitor of nitric oxide synthase, strongly contributes to endothelial dysfunction. In dialysis patients, ADMA levels are markedly elevated. Previous studies have shown that angiotensin-converting enzyme inhibitors (ACEIs) can significantly reduce ADMA levels in a variety of patients. In contrast, a previous study suggested that short-term treatment with ACEIs may even increase ADMA levels in adult patients on maintenance hemodialysis. However, no study has evaluated the effect of ACEIs in pediatric patients undergoing hemodialysis. Method We conducted a prospective, randomized, double-blinded and placebo-controlled trial (NCT04582097) at two nephrology centers in Cairo, Egypt. Patients below the age of 16 years and on regular hemodialysis for 6 months or longer were eligible for inclusion. Exclusion criteria at screening included uncontrolled hypertension, serum potassium level > 5.5 mmol/L, acute infection or treatment with immunosuppressive agents within the previous month, known intolerance of ACEI treatment and inability to discontinue previous ACEI or angiotensin receptor blocker treatment. A total of 135 eligible patients (mean age, 12.6 years; range 7-15 years; 53.3% males) were randomly (1:1) assigned to once oral daily treatment with identical capsules containing either 2.5 mg ramipril (n=68) or placebo (n=67) for four months. Systolic and diastolic blood pressure (BP) and serum ADMA concentrations were measured as primary efficacy and serum potassium levels as primary safety parameter. Results At baseline, systolic and diastolic BP and ADMA levels were similar between both treatment groups (Table). After four months, both systolic and diastolic BP were significantly lower in the ramipril compared to the placebo group. Treatment with ramipril resulted in a profound reduction in ADMA levels (-77% compared to baseline) while ADMA levels were unchanged in the placebo group after four months (p <0.001). Serum levels of potassium increase in both groups with no reported symptoms of severe hyperkalemia No serious adverse events were reported in neither group. Conclusion Ramipril treatment in pediatric patients on maintenance hemodialysis causes a marked reduction in ADMA levels. This may contribute to improved endothelial vascular function besides its efficacious BP lowering effect.

Download Full-text

Altered Purinergic Receptor Sensitivity in Type 2 Diabetes-Associated Endothelial Dysfunction and Up4A-Mediated Vascular Contraction

International Journal of Molecular Sciences ◽

10.3390/ijms19123942 ◽

2018 ◽

Vol 19 (12) ◽

pp. 3942 ◽

Cited By ~ 6

Author(s):

Ali Mahdi ◽

Tong Jiao ◽

Yahor Tratsiakovich ◽

Jiangning Yang ◽

Claes-Göran Östenson ◽

...

Keyword(s):

Endothelial Dysfunction ◽

Endothelial Function ◽

Vascular Function ◽

Purinergic Receptor ◽

Purinergic Signaling ◽

Mesenteric Arteries ◽

Vascular Contraction ◽

Gk Rats ◽

Vasoconstrictor Response

Purinergic signaling may be altered in diabetes accounting for endothelial dysfunction. Uridine adenosine tetraphosphate (Up4A), a novel dinucleotide substance, regulates vascular function via both purinergic P1 and P2 receptors (PR). Up4A enhances vascular contraction in isolated arteries of diabetic rats likely through P2R. However, the precise involvement of PRs in endothelial dysfunction and the vasoconstrictor response to Up4A in diabetes has not been fully elucidated. We tested whether inhibition of PRs improved endothelial function and attenuated Up4A-mediated vascular contraction using both aortas and mesenteric arteries of type 2 diabetic (T2D) Goto Kakizaki (GK) rats vs. control Wistar (WT) rats. Endothelium-dependent (EDR) but not endothelium-independent relaxation was significantly impaired in both aortas and mesenteric arteries from GK vs. WT rats. Non-selective inhibition of P1R or P2R significantly improved EDR in aortas but not mesenteric arteries from GK rats. Inhibition of A1R, P2X7R, or P2Y6R significantly improved EDR in aortas. Vasoconstrictor response to Up4A was enhanced in aortas but not mesenteric arteries of GK vs. WT rats via involvement of A1R and P2X7R but not P2Y6R. Depletion of major endothelial component nitric oxide enhanced Up4A-induced aortic contraction to a similar extent between WT and GK rats. No significant differences in protein levels of A1R, P2X7R, and P2Y6R in aortas from GK and WT rats were observed. These data suggest that altered PR sensitivity accounts for endothelial dysfunction in aortas in diabetes. Modulating PRs may represent a potential therapy for improving endothelial function.

Download Full-text

Protoporphyrin IX generation from δ-aminolevulinic acid elicits pulmonary artery relaxation and soluble guanylate cyclase activation

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00482.2005 ◽

2006 ◽

Vol 291 (3) ◽

pp. L337-L344 ◽

Cited By ~ 22

Author(s):

Christopher J. Mingone ◽

Sachin A. Gupte ◽

Joseph L. Chow ◽

Mansoor Ahmad ◽

Nader G. Abraham ◽

...

Keyword(s):

Guanylate Cyclase ◽

Vascular Function ◽

Soluble Guanylate Cyclase ◽

Aminolevulinic Acid ◽

Pulmonary Arteries ◽

Protoporphyrin Ix ◽

Physiological Mechanism ◽

No Donor ◽

Vasp Phosphorylation ◽

Guanylate Cyclase Activation

Protoporphyrin IX is an activator of soluble guanylate cyclase (sGC), but its role as an endogenous regulator of vascular function through cGMP has not been previously reported. In this study we examined whether the heme precursor δ-aminolevulinic acid (ALA) could regulate vascular force through promoting protoporphyrin IX-elicited activation of sGC. Exposure of endothelium-denuded bovine pulmonary arteries (BPA) in organoid culture to increasing concentrations of the heme precursor ALA caused a concentration-dependent increase in BPA epifluorescence, consistent with increased tissue protoporphyrin IX levels, associated with decreased force generation to increasing concentrations of serotonin. The force-depressing actions of 0.1 mM ALA were associated with increased cGMP-associated vasodilator-stimulated phosphoprotein (VASP) phosphorylation and increased sGC activity in homogenates of BPA cultured with ALA. Increasing iron availability with 0.1 mM FeSO4 inhibited the decrease in contraction to serotonin and increase in sGC activity caused by ALA, associated with decreased protoporphyrin IX and increased heme. Chelating endogenous iron with 0.1 mM deferoxamine increased the detection of protoporphyrin IX and force depressing activity of 10 μM ALA. The inhibition of sGC activation with the heme oxidant 10 μM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) attenuated the force depressing actions of an NO donor without altering the actions of ALA. Thus control of endogenous formation of protoporphyrin IX from ALA by the availability of iron is potentially a novel physiological mechanism of controlling vascular function through regulating the activity of sGC.

Download Full-text