Objectives The primary objective of this study was to elucidate mechanisms underlying the link between vitamin D status and cardiovascular disease by exploring the relationship between 25-hydroxyvitamin D (25-OH D), an established marker of vitamin D status, and vascular function in healthy adults. Background Mechanisms underlying vitamin D deficiency-mediated increased risk of cardiovascular disease remain unknown. Vitamin D influences endothelial and smooth muscle cell function, mediates inflammation, and modulates the renin-angiotensin-aldosterone axis. We investigated the relationship between vitamin D status and vascular function in humans, with the hypothesis that vitamin D insufficiency will be associated with increased arterial stiffness and abnormal vascular function. Methods We measured serum 25-OH D in 554 subjects. Endothelial function was assessed as brachial artery flow-mediated dilation, and microvascular function was assessed as digital reactive hyperemia index. Carotid-femoral pulse wave velocity and radial tonometry-derived central augmentation index and subendocardial viability ratio were measured to assess arterial stiffness. Results Mean 25-OH D was 31.8 ± 14 ng/ml. After adjustment for age, sex, race, body mass index, total cholesterol, low-density lipoprotein, triglycerides, C-reactive protein, and medication use, 25-OH D remained independently associated with flow-mediated vasodilation (β = 0.1, p = 0.03), reactive hyperemia index (β = 0.23, p < 0.001), pulse wave velocity (β = −0.09, p = 0.04), augmentation index (β = −0.11, p = 0.03), and subendocardial viability ratio (β = 0.18, p = 0.001). In 42 subjects with vitamin D insufficiency, normalization of 25-OH D at 6 months was associated with increases in reactive hyperemia index (0.38 ± 0.14, p = 0.009) and subendocardial viability ratio (7.7 ± 3.1, p = 0.04), and a decrease in mean arterial pressure (4.6 ± 2.3 mm Hg, p = 0.02). Conclusions Vitamin D insufficiency is associated with increased arterial stiffness and endothelial dysfunction in the conductance and resistance blood vessels in humans, irrespective of traditional risk burden. Our findings provide impetus for larger trials to assess the effects of vitamin D therapy in cardiovascular disease.

Objectives-The primary objective of this study was to elucidate mechanisms underlying the link between vitamin D status and cardiovascular disease by exploring the relationship between 25-hydroxyvitamin D (25-OH D), an established marker of vitamin D status, and vascular function in healthy adults. Background-Mechanisms underlying vitamin D deficiency-mediated increased risk of cardiovascular disease remain unknown. Vitamin D influences endothelial and smooth muscle cell function, mediates inflammation, and modulates the renin-angiotensin-aldosterone axis. We investigated the relationship between vitamin D status and vascular function in humans, with the hypothesis that vitamin D insufficiency will be associated with increased arterial stiffness and abnormal vascular function. Methods-We measured serum 25-OH D in 554 subjects. Endothelial function was assessed as brachial artery flow-mediated dilation, and microvascular function was assessed as digital reactive hyperemia index. Carotid-femoral pulse wave velocity and radial tonometry-derived central augmentation index and subendocardial viability ratio were measured to assess arterial stiffness. Results-Mean 25-OH D was 31.8 ± 14 ng/ml. After adjustment for age, sex, race, body mass index, total cholesterol, low-density lipoprotein, triglycerides, C-reactive protein, and medication use, 25-OH D remained independently associated with flow-mediated vasodilation (β = 0.1, p = 0.03), reactive hyperemia index (β = 0.23, p < 0.001), pulse wave velocity (β = −0.09, p = 0.04), augmentation index (β = −0.11, p = 0.03), and subendocardial viability ratio (β = 0.18, p = 0.001). In 42 subjects with vitamin D insufficiency, normalization of 25-OH D at 6 months was associated with increases in reactive hyperemia index (0.38 ± 0.14, p = 0.009) and subendocardial viability ratio (7.7 ± 3.1, p = 0.04), and a decrease in mean arterial pressure (4.6 ± 2.3 mm Hg, p = 0.02).

We had previously suggested that women with endometriosis have increased oxidative stress in the peritoneal cavity. In order to assess whether antioxidant supplementation would ameliorate endometriosis associated symptoms, we performed a randomized, placebo controlled trial of antioxidant vitamins (Vitamin E and C) in women with pelvic pain and endometriosis. Fifty nine women, ages 19–41 years, with pelvic pain and history of endometriosis and/or infertility were recruited for this study. Patients were randomly assigned to two groups: vitamin E (1200 IU) and vitamin C (1000 mg) combination or placebo, daily for eight weeks before surgery. Pain scales were administered at baseline and bi-weekly. Inflammatory markers were measured in the peritoneal fluid obtained from both groups of patients at the end of therapy. Our results indicated that, after treatment with antioxidants, chronic pain (“everyday pain”) improved in 43% of patients in antioxidant treatment group (p=0.0055) as compared to the placebo group. In the same group, dysmenorrhea (“pain associated with menstruation”) and dyspareunia (“pain with sex”) decreased in 37% and 24% patients, respectively. In the placebo group, dysmenorrhea associated pain decreased in 4 patients and no change was seen in chronic pain or dyspareunia. There was significant decrease in peritoneal fluid inflammatory markers, RANTES (p≤0.002), interleukin-6 (p≤0.056) and monocyte chemotactic protein-1 (p≤0.016) after antioxidant therapy compared to patients not on antioxidants. In conclusion, results of this clinical trial show that administration of antioxidants reduces chronic pelvic pain in women with endometriosis and inflammatory markers in the peritoneal fluid.

Aims Arterial stiffening may lead to hypertension, greater left ventricular after-load and adverse clinical outcomes. The underlying mechanisms influencing arterial elasticity may involve oxidative injury to the vessel wall. We sought to examine the relationship between novel markers of oxidative stress and arterial elastic properties in healthy humans. Methods & Results We studied 169 subjects (mean age 42.6 ± 14 years, 51.6% male) free of traditional cardiovascular risk factors. Indices of arterial stiffness and wave reflections measured included carotid-femoral Pulse Wave Velocity (PWV), Augmentation index (Aix) and Pulse Pressure Amplification (PPA). Non-free radical oxidative stress was assessed as plasma oxidized and reduced amino-thiol levels (cysteine/cystine, glutathione/GSSG) and their ratios (redox potentials), and free radical oxidative stress as derivatives of reactive oxygen metabolites (dROMs). Inflammation was assessed as hsCRP and interleukin-6 levels. The non-free radical marker of oxidative stress, cystine was significantly correlated with all arterial indices; PWV (r= 0.38, p<0.001), Aix (r=0.35, p<0.001) and PPA (r=−0.30, p<0.001). Its redox potential, was also associated with PWV (r=0.22, p=0.01), while the free radical marker of oxidative stress dROMS was associated with Aix (r=0.25, p<0.01). After multivariate adjustment for age, gender, arterial pressure, height, weight, heart rate and CRP, of these oxidative stress markers, only cystine remained independently associated with PWV (p=0.03), Aix (p=0.01) and PPA (p=0.05). Conclusions In healthy subjects without confounding risk factors or significant systemic inflammation, a high cystine level, reflecting extracellular oxidant burden, is associated with increased arterial stiffness and wave reflections. This has implications for understanding the role of oxidant burden in pre-clinical vascular dysfunction.

Background We assessed the contribution of endothelium-derived hyperpolarizing factors (EDHFs) to resting and agonist-stimulated vasodilator tone in health and disease. Tetraethylammonium chloride (TEA) was employed to inhibit K+Ca channel activation and fluconazole to inhibit cytochrome P450 2C9-mediated epoxyeicosatrienoic acid synthesis. We hypothesized that 1) EDHFs contribute to resting vascular tone by K+Ca channel activation and epoxyeicosatrienoic acid release, and 2) EDHFs compensate for reduced nitric oxide bioavailability at rest and with endothelium-dependent vasodilators. Methods and Results In 103 healthy subjects and 71 non-hypertensive subjects with multiple risk factors, resting forearm blood flow (FBF) was measured using venous occlusion plethysmography before and after intra-arterial infusions of NG-monomethyl-L-arginine (L-NMMA), TEA, fluconazole, and their combination. The effects of these antagonists on resting FBF, and on bradykinin- and acetylcholine-mediated vasodilation was studied. Resting FBF decreased with TEA and L-NMMA in all subjects (P<0.001), however, the vasoconstrictor response to L-NMMA was greater (p=0.04) and to TEA lower (p=0.04) in healthy subjects compared to those with risk factors. Fluconazole decreased resting FBF in all subjects and addition of TEA further reduced FBF after fluconazole, suggesting that cytochrome P450 metabolites and other hyperpolarizing factor(s) activate K+Ca channels. Both L-NMMA and TEA attenuated bradykinin-mediated vasodilation in healthy and hypercholesterolemic subjects (P<0.001). In contrast, acetylcholine-mediated vasodilation remained unchanged with TEA in healthy subjects, but was significantly attenuated in hypercholesterolemia (P<0.04). Conclusions Firstly, EDHFs by activating TEA inhibitable K+Ca channels together with NO contribute to resting microvascular dilator tone. The contribution of K+Ca channel activation compared to NO is greater in those with multiple risk factors compared to healthy subjects. Second, activation of K+Ca channels is only partly through epoxyeicosatrienoic acid release, indicating presence of other hyperpolarizing mechanisms. Third, bradykinin, but not acetylcholine stimulates K+Ca channel-mediated vasodilation in healthy subjects, whereas in hypercholesterolemia, K+Ca channel-mediated vasodilation compensates for the reduced NO activity. Thus, enhanced EDHF activity in conditions of NO deficiency contributes to maintenance of resting and agonist-stimulated vasodilation. Clinical Trial Registration Information: http://clinicaltrials.gov/, Identifier: NCT00166166