Endothelium-dependent vasodilation in relation to different measurements of blood pressure in the elderly: the prospective investigation of the Vasculature in Uppsala Seniors study:

Platelet counts are associated with arterial stiffness in Chinese Han population: a longitudinal study

Background

Determining the risk factors for brachial-ankle pulse wave velocity (baPWV) may help to identify people susceptible to diabetic atherosclerosis and could prevent diabetic macrovascular complications in the early stages. We aim to comprehensively investigate risk factors contributing to arterial stiffness in patients with and without diabetes.

Methods

BaPWV was measured in 5651 individuals who attended health check-ups at baseline and follow-up. Lasso regression was used to screen for risk factors. Mixed models and multiple linear regressions were subsequently established to evaluate the effect size of the potential risk factors on baPWV and PWV change rates. All analyses were stratified by diabetes. Mediation analysis was also conducted to demonstrate the mechanisms of arterial stiffness in patients with diabetes.

Results

In lasso regression, postprandial 2-h glucose (P2hG), systolic blood pressure (SBP) and age were associated with baPWV regardless of diabetes. Platelet counts (PLT), mean corpuscular volume (MCV) and coronary heart disease (CHD) were associated with baPWV in patients with diabetes. In the mixed models, PLT were positively associated with baPWV in patients with diabetes (β_{platelet, perSD} = 25.80; 18.26–33.33). Elevated PLTs could also significantly increase the PWV change rate in patients with diabetes (β_{platelet, perSD} = 54.05; 10.00–107.10). In mediation analysis, diabetes had a significant average direct effect on baPWV. The average causal mediation effect (ACME) of PLTs was 1.76, with a range of 0.17 to 3.70.

Conclusions

Elevated PLT counts can increase baPWV in diabetes and are a potential mediator between diabetes and atherosclerosis.

Associations of central aortic pressure and brachial blood pressure with flow mediated dilatation in apparently healthy Japanese men: The Circulatory Risk in Communities Study (CIRCS)

BACKGROUND AND AIMS

Endothelial dysfunction is considered the first stage in the development of atherosclerosis and cardiovascular disease, and brachial flow-mediated dilation (FMD) is a measure of endothelial function. It is uncertain which of central systolic aortic pressure (CAP) or brachial systolic blood pressure (SBP) is more strongly associated with FMD. Therefore, we examined the correlations of CAP and SBP with FMD in Japanese men.

METHODS

The study subjects comprised 507 male volunteers aged 30-79 years that were residents in two communities under the Circulatory Risk in Communities Study (CIRCS) between 2013 and 2015. The low percent change of FMD (%FMD) ≤5.0%, after 5 min of reactive hyperemia evaluated by the brachial artery diameter, was used to assess endothelial dysfunction. Values of CAP and SBP were divided into tertiles, with the lowest tertile used as a reference.

RESULTS

After adjustment for cardiovascular risk factors, the multivariable odds ratio (95% CI) of low FMD for the highest versus lowest tertile of CAP was 1.5 (0.9-2.6) for total subjects and 1.4 (0.5-3.8) for those with, and 2.4 (1.2-4.8) for those without antihypertensive medication use. The corresponding odd ratios for the highest versus lowest tertile of SBP were 0.9 (0.5-1.5), 0.8 (0.3-2.2), and 1.3 (0.7-2.5), respectively.

CONCLUSIONS

Higher CAP levels were associated with low FMD for men without antihypertensive medication, but such an association was not found for SBP levels.

Vitamin D induces increased systolic arterial pressure via vascular reactivity and mechanical properties

Background/Aims

The aim of this study was to evaluate whether supplementation of high doses of cholecalciferol for two months in normotensive rats results in increased systolic arterial pressure and which are the mechanisms involved. Specifically, this study assesses the potential effect on cardiac output as well as the changes in aortic structure and functional properties.

Methods

Male Wistar rats were divided into three groups: 1) Control group (C, n = 20), with no supplementation of vitamin D, 2) VD3 (n = 19), supplemented with 3,000 IU vitamin D/kg of chow; 3) VD10 (n = 21), supplemented with 10,000 IU vitamin D/kg of chow. After two months, echocardiographic analyses, measurements of systolic arterial pressure (SAP), vascular reactivity, reactive oxygen species (ROS) generation, mechanical properties, histological analysis and metalloproteinase-2 and -9 activity were performed.

Results

SAP was higher in VD3 and VD10 than in C rats (p = 0.001). Echocardiographic variables were not different among groups. Responses to phenylephrine in endothelium-denuded aortas was higher in VD3 compared to the C group (p = 0.041). Vascular relaxation induced by acetylcholine (p = 0.023) and sodium nitroprusside (p = 0.005) was impaired in both supplemented groups compared to the C group and apocynin treatment reversed impaired vasodilation. Collagen volume fraction (<0.001) and MMP-2 activity (p = 0.025) was higher in VD10 group compared to the VD3 group. Elastin volume fraction was lower in VD10 than in C and yield point was lower in VD3 than in C.

Conclusion

Our findings support the view that vitamin D supplementation increases arterial pressure in normotensive rats and this is associated with structural and functional vascular changes, modulated by NADPH oxidase, nitric oxide, and extracellular matrix components.

Does the DASH diet lower blood pressure by altering peripheral vascular function?

We tested whether lowering of blood pressure (BP) on the dietary approaches to stop hypertension (DASH) diet was associated with changes in peripheral vascular function: endothelial function, assessed by flow-mediated vasodilatation (FMD) of the brachial artery, and subcutaneous adipose tissue blood flow (ATBF). We also assessed effects on heart rate variability (HRV) as a measure of autonomic control of the heart. We allocated 27 men and women to DASH diet and control groups. We measured FMD, ATBF and HRV on fasting and after ingestion of 75 g glucose, before and after 30 days on dietary intervention, aiming for weight maintenance. The control group did not change their diet. The DASH-diet group complied with the diet as shown by significant reductions in systolic (P<0.001) and diastolic (P=0.005) BP, and in plasma C-reactive protein (P<0.01), LDL-cholesterol (P<0.01) and apolipoprotein B (P=0.001), a novel finding. Body weight changed by <1 kg. There were no changes in the control group. We found no changes in FMD, or in ATBF, in the DASH-diet group, although heart rate fell (P<0.05). Glucose and insulin concentrations did not change. In this small-scale study, the DASH diet lowered BP independently of peripheral mechanisms.