EFFECTS OF AGE ON LIMB ARTERIAL COMPLIANCE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Many different types of changes in the vascular system may be at the heart of decreased blood vessel function with aging in humans. A key factor in this decrement in function appears to be changes in mechanical properties of the vessel walls and how they respond to blood pressure changes. Compliance of blood vessels is their distensibility in response to pressure changes inside them, i.e. how much the vessel walls move every time the heart beats. We have developed a software that can simultaneously record blood pressure tracings from a noninvasive blood pressure monitor and changes in calf volume from a noninvasive surface strain gauge every time the heart beats to derive whole calf compliance. This project will combine this technology with the method generally used to assess single vessel compliance using Doppler ultrasound and noninvasive blood pressure monitoring to compare whole calf compliance with that of the major artery feeding the calf vascular bed, the popliteal artery. This will be done to compare age-related changes in vessel compliance (from Doppler imaging and blood pressure tracings) with age-related changes in whole limb compliance (from surface strain gauge and blood pressure tracings) which reflects changes in the large vessels in the limb and the small vasculature that cannot be easily studied on its own. Measurements will be made during rest and moderate heating (about the temperature of a common sauna) of one calf and foot only to induce a locally higher blood flow without causing any cardiovascular distress or discomfort.