Effect of exercise and ageing on the vasculature in humans : conduit and microvascular function in the upper limb of young, older sedentary and older fit men and women

• Main Author: Black, Mark Adam
• Published: Liverpool John Moores University 2008
• Subjects: 612.171
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494048

The aim of this thesis was to investigate the impact of age, sex and fitness on nitric oxide (NO)-mediated endothelial function on upper-limb conduit and skin microvessels. Age-related dysfunction of the cardiovascular system increases the likelihood of cardiovascular disease and associated morbidity and mortality. A key early stage in cardiovascular dysfunction is attenuation in the bioactivity of NO, a molecule that is released by the endothelium of all blood vessels throughout the vascular tree. NO is a potent vasodilator which possesses anti-atherogenic properties including inhibition of platelet aggregation and adhesion and vascular smooth muscle cell proliferation. Flow-mediated dilatation (FMD), an index of conduit artery nitric oxide-(NO) mediated vasodilator function, is regarded as a surrogate marker of cardiovascular disease. Ageing is associated with conduit artery endothelial dysfunction; however underlying sex-related differences may exist. Furthermore, the effects of fitness and exercise on endothelial dysfunction in men and women are poorly understood. FMD of the brachial artery was performed in 18 young (Y, 26 ± 1yrs, 9M 9W), 12 older fit (OF, 57 + 2 yrs, 6M 6W) and 16 older sedentary (OS, 59 ± 1 yrs, 8M 8W) subjects using duplex ultrasound and edge detection software for continuous measures of arterial diameter and blood flow velocity estimates. Glyceryl trinitrate (GTN) administration was used to assess endothelium-independent mediated vasodilatation and the FMD/GTN ratio calculated to characterise NO dilator function in the context of smooth muscle cell sensitivity. Brachial FMD% in Y (7.1 ± 0.8%) was significantly higher compared with OS (4.8 ± 0.7 %, P<0.05), but not OF (6.4 ± 0.7 %]). Differences between Y and OS subjects were due primarily to lower FMD in the OS women 4.3 ± 0.6%.