Erik Salum

Vitamin D reduces deposition of advanced glycation end-products in the aortic wall and systemic oxidative stress in diabetic rats

AIMS Vitamin D may have an important role in reducing the risk of cardiovascular disease. Advanced glycation end-products (AGEs) such as Nε-(carboxymethyl)lysine (CML), have been implicated in diabetic vascular complications via oxidative stress-mediated pathways. We investigated the potential protective effect of vitamin D on CML accumulation in the diabetic aortic wall. To test the effects of vitamin D on systemic oxidative stress we also assessed liver oxidative stress index (OSI) and serum total antioxidant capacity (TAC). METHODS Male Wistar rats were assigned to three groups: control, untreated diabetes, and diabetes+cholecalciferol. Diabetes was induced by streptozotocin, followed by oral administration of cholecalciferol (500 IU/kg) for 10 weeks in the treatment group. Aortic CML accumulation was determined by ELISA and immunohistochemical assays. OSI was assessed by measuring TAC and the level of total peroxides in the liver and serum using colorimetric assays. RESULTS Untreated diabetes was associated with significantly elevated CML levels in the aortic wall (19.5 ± 3.3 vs 10.2 ± 4.7 ng/mL), increased liver OSI (6.8 ± 1.9 vs 3.1 ± 0.7), and reduced serum TAC (0.4 ± 0.1 vs 0.8 ± 0.3 mmol Trolox/L), in comparison with the control group. Cholecalciferol significantly blocked the accumulation of CML in the aortic wall (10.4 ± 8.4 vs 19.5 ± 3.3 ng/mL), decreased liver OSI (4.2 ± 1.4 vs 6.8 ± 1.9), and improved serum TAC (1.0 ± 0.2 vs 0.4 ± 0.1 mmol Trolox/L), compared with the untreated diabetic group. CONCLUSIONS Streptozotocin-diabetes resulted in increased deposition of AGEs and increased oxidative stress in the serum and liver. Vitamin D supplementation may provide significant protection against oxidative stress-mediated vascular complications in diabetes.

Effect of vitamin D on aortic remodeling in streptozotocin-induced diabetes

BackgroundDiabetes mellitus is associated with micro- and macrovascular complications and increased cardiovascular risk. Elevated levels of serum asymmetric dimethylarginine (ADMA) may be responsible for endothelial dysfunction associated with diabetes-induced vascular impairment. Vitamin D may have potential protective effects against arterial stiffening. This study aimed to examine both the effects of diabetes on the functional/structural properties of the aorta and the endothelial function and the effects of vitamin D supplementation.MethodsMale Wistar rats (n = 30) were randomly assigned to control untreated, diabetic untreated, and diabetic + cholecalciferol groups. Diabetes was induced by intraperitoneal injection of streptozotocin, followed by oral administration of cholecalciferol (500 IU/kg) for 10 weeks in the treatment group. Aortic pulse wave velocity (PWV) was recorded over a mean arterial pressure (MAP) range of 50 to 200 mmHg using a dual pressure sensor catheter. Intravenous infusion of phenylephrine and nitroglycerine was used to increase and decrease MAP, respectively. Serum 25-hydroxyvitamin D [25(OH)D] levels were measured using a radioimmune assay. ADMA levels in serum were measured by enzyme-linked immunoassay. Aortic samples were collected for histomorphometrical analysis.ResultsPWV up to MAP 170 mmHg did not reveal any significant differences between all groups, but in diabetic rats, PWV was significantly elevated across MAP range between 170 and 200 mmHg. Isobaric PWV was similar between the treated and untreated diabetic groups, despite significant differences in the levels of serum 25(OH)D (493 ± 125 nmol/L vs 108 ± 38 nmol/L, respectively). Serum levels of ADMA were similarly increased in the treated and untreated diabetic groups, compared to the control group. The concentration and integrity of the elastic lamellae in the medial layer of the aorta was impaired in untreated diabetic rats and improved by vitamin D supplementation.ConclusionPWV profile determined under isobaric conditions demonstrated differential effects of uncontrolled diabetes on aortic stiffness. Diabetes was also associated with elevated serum levels of ADMA. Vitamin D supplementation did not improve the functional indices of aortic stiffness or endothelial function, but prevented the fragmentation of elastic fibers in the aortic media.

Association between asymmetric dimethylarginine and indices of vascular function in patients with essential hypertension.

Abstract Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase and is associated with endothelial dysfunction. The aim of the present study was to investigate the relationship between ADMA, indices of arterial stiffness, endothelial function and carotid artery intima-media thickness (IMT) in hypertension patients. Eighty middle-aged (47 ± 10 years) untreated patients with mild to moderate essential hypertension underwent routine physical examination, pulse wave analysis (PWA), measurement of aortic pulse wave velocity (PWV) and IMT. In PWA, administration of salbutamol and nitroglycerine was used to assess endothelium-dependent (EDV) and endothelium-independent vasodilation, respectively. In univariate analysis, ADMA was correlated with EDV (r = −0.26; p = 0.02) and IMT (r = 0.32; p = 0.007). In multiple regression analysis, ADMA was independently associated with the female gender, EDV, IMT and total cholesterol (R2 = 0.30; p < 0.001). No correlation was detected between ADMA and augmentation index, central/brachial blood pressure or aortic PWV. In hypertension patients, ADMA is independently correlated with IMT and EDV. Thus, ADMA is a marker of endothelial dysfunction and intima-media thickening in patients with hypertension.

Effects of a long-term military mission on arterial stiffness, inflammation markers, and vitamin D level

vitamin D level Erik Salum ⁎, Mihkel Zilmer , Priit Kampus , Jaak Kals , Eve Unt , Martin Serg , Maksim Zagura , Mai Blöndal , Kersti Zilmer , Jaan Eha a,b a Department of Cardiology, University of Tartu, 8 Puusepa Street, Tartu 51014, Estonia b Endothelial Centre, University of Tartu, 8 Puusepa Street, Tartu 51014, Estonia c Department of Biochemistry, Centre of Excellence for Translational Medicine, University of Tartu, 19 Ravila Street, Tartu 50411, Estonia d Department of Vascular Surgery, Tartu University Hospital, 8 Puusepa Street, Tartu 51014, Estonia e Institute of Exercise Biology and Physiotherapy, University of Tartu, 14a Ravila Street, Tartu 50411, Estonia f Department of Sports Medicine and Rehabilitation, University of Tartu, 5 Jakobi Street, Tartu 50090, Estonia

Effects of anti-hypertensive treatment on functional and structural components of large artery stiffness and retinal vessel diameters in a rodent model of type I diabetes

### CONTRIBUTION OF THE AREA POSTREMA TO THE INCREASED CARDIAC SYMPATHETIC NERVE ACTIVITY IN OVINE HEART FAILURE Abukar Y, Ramchandra R, May CN The Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia Background : Heart failure (HF) is associated with an increase in cardiac sympathetic nerve activity (CSNA), which is directly linked to mortality in HF patients. The mechanisms responsible for the elevated CSNA remain unclear. Previous studies indicate that the area postrema (AP), a circumventricular organ in the brainstem, plays a role in the control of sympathetic nerve activity. We hypothesized that the elevated CSNA in HF is mediated by the AP and lesioning this region would reduce the increased CSNA in sheep with HF. Aims : To determine the effect of sham lesion or lesion of the AP on CSNA and hemodynamics in conscious sheep with HF. Methods : Studies were conducted in 2 groups of sheep with pacing-induced HF: sham (n=6) and AP lesion (n=6) sheep. Mean arterial blood pressure (MAP), heart rate (HR) and CSNA were recorded simultaneously in conscious sheep at least 4 days after surgery. Results : Heart failure was associated with a significant decrease in ejection fraction (from 74±2 % to 38±1 %; P<0.001), which was similar in both groups. There was a significant reduction in CSNA burst incidence in the AP lesion group compared with the sham group (45±10 and 89±3 bursts/100 heartbeats, respectively; P<0.01). Conclusions : In sheep with HF, the group with lesion of the AP had a significantly lower CSNA compared with the sham group. These data suggest that the AP plays a role in setting the detrimental high levels of CSNA in HF. ### G PROTEIN-COUPLED ESTROGEN RECEPTOR SIGNALING IMPROVES STROKE OUTCOME IN FEMALE MICE Broughton BRS, Jansen GL, Sobey CG Department of Pharmacology, Monash University, Clayton, Victoria, Australia Background: Estrogen has been assumed to provide neuroprotection following stroke entirely via classical estrogen receptors. Interestingly, there is recent evidence that activation of a novel G …

541 VITAMIN D ATTENUATES OXIDATIVE STRESS IN A RAT MODEL OF DIABETES-INDUCED AORTIC STIFFNESS

Background: Emerging evidence suggests that increased oxidative stress is implicated in the diabetic macrovascular complications. This study aimed to examine the effects of diabetes on the elastic properties of the aorta and the protective effects of vitamin D supplementation. Methods: Diabetes was induced by streptozotocin, followed by oral administration of cholecalciferol (500 IU/kg) for 10 weeks. Aortic pulse wave velocity (PWV) was recorded over a mean arterial pressure (MAP) range of 50 to 200 mmHg using a dual pressure sensor catheter. Oxidative stress index (OSI) was assessed by measuring total antioxidant capacity (TAC) and the level of total peroxides in the liver and serum. Advanced glycation end-products (AGEs) were determined in aortic samples by an immunochemical assay. Results: In diabetic rats, PWV was significantly elevated across MAP range between 170 and 200 mmHg, compared to control rats (7.0 ± 0.5 m/s vs 5.7 ± 0.7 m/s at MAP 170 mmHg, respectively, P < 0.05). PWV across lower MAP range did not reveal any significant differences between all groups. Diabetes was associated with significantly increased OSI in the liver and AGEs in the aorta, and reduced TAC in the serum. Cholecalciferol did not improve aortic stiffness, despite high levels of 25(OH)D in the treatment group. Changes in biomarkers of oxidative stress were significantly improved by cholecalciferol. Conclusion: PWV profile determined under isobaric conditions demonstrated differential effects of uncontrolled diabetes on aortic stiffness. Diabetes was also accompanied by increased oxidative stress. Vitamin D did not improve aortic stiffness, but attenuated oxidative stress in diabetic rats. Table. No title available.

150 STRUCTURAL AND BIOCHEMICAL CHARACTERISTICS OF ARTERIAL STIFFNESS IN PATIENTS WITH ATHEROSCLEROSIS AND IN HEALTHY SUBJECTS

Background: Arterial stiffness is an independent predictor of vascular morbidity and mortality in patients with atherosclerosis. Angiographic score (ASc) reflects severity of atherosclerosis in patients with peripheral arterial disease (PAD). Osteopontin (OPN) and oxidized LDL (oxLDL) are involved in the pathogenesis of atherosclerosis. The aim of the present study was to evaluate the association between arterial stiffness, ASc, serum OPN, and oxLDL in patients with symptomatic PAD and in clinically healthy subjects. Methods: We studied 79 men with symptomatic PAD (mean age 64±7 years) and 84 healthy men (mean age 64±8 years). The diagnosis of PAD was confirmed by the ankle-brachial pressure index (ABPI) and digital subtraction angiography. Calculation of the ASc was based on severity and location of atherosclerotic lesions in the arteries of the lower extremities. Aortic pulse wave velocity (aPWV) was evaluated by applanation tonometry using the Sphygmocor device. Serum OPN and oxLDL levels were determined by ELISA. Results: The aPWV (10±2.4 vs. 8.6±1.6 (m/s);p<0.001), OPN (75(62.3–85.8) vs. 55.8(45.2–70.9) (ng/ml);p<0.001), and oxLDL (67(52.5–93.5) vs. 49.5(37.1–67.5);p<0.001) were different for the patients and for the controls. In multiple regression models, aPWV was independently determined by ASc, log-OPN, log-oxLDL, eGFR, and age in the patients (R2=0.45;p<0.001) and with log-OPN, log-oxLDL, age, and heart rate in the controls (R2=0.39;p<0.001). Conclusion: The independent relationship between aPWV and serum levels of OPN and oxLDL in patients with PAD and in controls indicate that OPN and oxLDL might be involved in the pathogenesis of arterial stiffness in atherosclerosis and in clinically healthy subjects.