Browsing by Subject "Vascular function"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item The contribution of whole blood viscosity in assessment of vascular function(2011-05) Parkhurst, Kristin Louise; Tanaka, Hirofumi, Ph. D.; Farrar, RogerAlthough blood viscosity is an important component in determining vascular function, it is often assumed constant. Emerging evidence linking individual differences in viscosity to cardiovascular disease casts doubt on this assumption. The purpose of this study was to determine the contribution of whole blood viscosity to key measures of vascular function. To address this aim as comprehensively as possible, first, whole blood viscosity was compared with traditional risk factors for cardiovascular disease. Then flow-mediated dilation (FMD), carotid-femoral pulse wave velocity (cfPWV), and carotid artery compliance were calculated either with or without blood viscosity taken into account. Lastly, we tested whether the removal of blood viscosity could influence well-established associations between age and vascular function. Blood viscosity and vascular function were measured in 97 adults ranging in age from 18-63 years. No significant differences were observed between whole blood viscosity and traditional risk factors for cardiovascular disease. Whole blood viscosity was not significantly correlated with FMD, cfPWV, and carotid compliance. As expected, age was positively correlated with cfPWV (r=0.65, p<0.001) and negatively correlated with FMD (r=-0.21, p<0.05) and carotid compliance (r=-0.45, p<0.01). Even after controlling for viscosity, these relationships remained statistically significant (cfPWV r=0.65, p<0.001; FMD r=-0.24, p<0.05; carotid compliance r=-0.44, p<0.05). These results indicate that whole blood viscosity does not appear to significantly impact measures of vascular function and that the rationale for including whole blood viscosity in the calculation of vascular function remains weak.Item The effects of acute muscle damage and autoimmune disease on vascular function : the potential role of inflammation(2009-08) Barnes, Jill Nicole; Tanaka, Hirofumi, Ph. D.Inflammation has been implicated in the development of cardiovascular disease and a potential underlying mechanism in the pathogenesis of impaired vascular function. Two different but complementary approaches were utilized to determine the role of inflammation on vascular function. First, to evaluate the effect of acute inflammation, we induced muscle damage to both small and large muscle mass and measured vascular function every 24 hours for up to 5 days of recovery. Eccentric exercise-induced muscle damage, in both small and large muscle mass, resulted in a transient increase in central arterial stiffness. Next, patients with systemic lupus erythematosus (SLE) were studied as a model of chronic inflammation. Measurements of vascular function were compared in habitually-exercising and sedentary SLE patients, and age-matched healthy controls. Individuals with SLE demonstrated lower vascular function than healthy controls. When SLE patients were grouped by exercise status, habitually-exercising SLE patients exhibited similar vascular function to healthy controls, and lower overall disease activity compared with sedentary SLE patients, supporting the beneficial effect of regular exercise in this population. Inflammatory biomarkers were associated with measures of macro- and microvascular function. In conclusion, acute muscle damage and chronic disease-related inflammation have a potent effect on measures of vascular function, suggesting that inflammation plays a role in the pathogenesis of vascular dysfunction and is an important biomarker for cardiovascular risk.Item The hypotensive effects of conventional non-fat dairy products : the role of arterial stiffness(2014-08) Machin, Daniel Robert; Tanaka, Hirofumi, Ph. D.High consumption of dairy products, particularly non-fat dairy, is associated with reduced risk of high blood pressure and vascular dysfunction. Currently, it is not known if the solitary addition of conventional non-fat dairy products to the normal routine diet is capable of reducing blood pressure or improving vascular function. Accordingly, the primary aims of the present study were to determine if the solitary addition of conventional non-fat dairy products to the normal routine diet would reduce blood pressure and improve vascular function in middle-aged and older adults with elevated blood pressure. Using a randomized, crossover intervention study design, forty-nine adults with elevated blood pressure underwent a High Dairy condition (+4 servings/day of conventional non-fat dairy products) and isocaloric No Dairy condition (+4 servings/day fruit products) in which all dairy products were removed. Both dietary conditions lasted 4 weeks with a 2-week washout before crossing over into the alternate condition. In Study 1, the High Dairy condition produced reductions in brachial systolic blood pressure and pulse pressure. The hypotensive effects were observed within three weeks after the initiation of dietary intervention and in both casual seated and ambulatory (24-hour) measurements. On the contrary, pulse pressure was increased after removal of all dairy products in the No Dairy condition compared to baseline and after in the High Dairy condition. There were no changes in diastolic blood pressure after either dietary condition. In Study 2, the High Dairy condition produced reductions in carotid systolic blood pressure, pulse pressure, and carotid-femoral pulse wave velocity with a concomitant increase in brachial flow-mediated dilation and cardiovagal baroreflex sensitivity. Brachial flow-mediated dilation decreased and carotid pulse pressure increased after removal of all dairy products in the No Dairy condition. Furthermore, [delta] carotid systolic blood pressure and carotid-femoral pulse wave velocity were highly related. Taken together, we concluded that the solitary manipulation of conventional dairy products, particularly non-fat dairy, in the normal routine diet would modulate levels of blood pressure and vascular function in middle-aged and older adults with pre-hypertension and hypertension.Item Regular aerobic exercise and cognitive function : the roles of vascular function and plasma insulin(2012-08) Tarumi, Takashi; Tanaka, Hirofumi, Ph. D.; Haley, Andreana P.; Ress, David; Machart, Jan M.; Brothers, Robert M.There is an increasing recognition that vascular disease risk is associated with a greater incidence of cognitive impairment and dementia. Such link is supported by the physiological observation that cerebral metabolism heavily relies on vascular supply of oxygen and energy substrates. Cerebral hypoperfusion which results from vascular dysfunction causes a mismatch between energy demand and supply and is associated with the pathological features of dementia, including the impairments of action potential generation and protein synthesis, glutamatergic excitotoxicity, and the deposition of cerebral amyloid-β proteins. In contrast, habitual aerobic exercise is an established strategy to ameliorate the risk factors for vascular disease and is increasingly recognized in improving cognitive function. Accordingly, the primary purpose of this dissertation study was to investigate whether the exercise-related improvement in cognitive function was attributable to ameliorated vascular function and risk factors for vascular disease. In order to address this as comprehensively as we could, both cross-sectional and interventional studies were conducted. The primary findings from the present study were as follows. In the cross-sectional study, a greater cognitive performance observed in endurance-trained adults was associated with higher levels of cerebral CO2 reactivity and brachial endothelium-dependent vasodilation and lower levels of central arterial stiffness and plasma insulin. In the interventional study, a 3-month aerobic exercise training intervention did not improve cognitive function although central arterial stiffness and brachial endothelium-dependent vasodilation made favorable changes. However, we found that the improvement in memory performance after aerobic exercise training was associated with the reduction in central systolic blood pressure. Taken together, a better cognitive performance observed in endurance-trained adults may not directly be attributable to greater vascular function because there were discrepant changes in cognitive and vascular functions after a 3-month aerobic exercise intervention. The correlation between the changes in memory performance and central systolic blood pressure is interesting but needs further investigation using a larger sample size. The discrepancy in the results between the cross-sectional and interventional studies could be explained by the duration of exercise training and/or the time it takes for the effect of improved vascular function to translate into cognitive function.