Preliminary research indicates there is some impairment of the endothelial cells to respond to single stressors such as local heat, shear stress, and global heat in older people and people who have diabetes. The response of the skin blood flow to local heat is an indicator of the endothelial cells ability to cope with stress. In addition, factors such as thicker subcutaneous fat and skin moisture may impair the skin’s ability to dissipate heat. For older people and people with diabetes, this endothelial dysfunction may cause an even more diminished response to multiple stressors. However, no studies have examined the effects of multiple stressors on the response of the endothelial cell in these same populations. Therefore, the purpose of this research was to build on previous studies by looking at multiple stressors, including heat dissipation, local pressure, global heat, and local heat, applied simultaneously. In these studies, older non-diabetic subjects (mean age 64.2±14.0 yrs, n=15), subjects with diabetes (mean age 62±5.9 yrs, mean duration 13.2±9.1 yrs, n=15), and younger non-diabetic subjects (mean age 25.7±2.9 yrs, n=15) participated. Subjects were exposed to three temperatures of global heat: 16°, 24°, and 32°C. The first study examined the effects of global heat and local heat with a set calorie heat load on the ability of the skin to dissipate the heat. The results indicated an inability of the endothelial cells to respond to multiple stressors in older people and people with diabetes. From this study, two subsequent studies were designed to look at the effects of multiple stressors on the response of the endothelial cells. First, the effects and interaction of local heat and global heat were examined. We found the response of the endothelial cells in older people and people with diabetes reached a plateau after a combined stress was placed on them. Secondly, the effects of another type of endothelial stressor, shear stress, were examined by applying different pressures to the skin and measuring the pressure-induced vasodilation (PIV). The results showed a reduction in the PIV response of the subjects with diabetes in all global temperatures indicating an inability to respond to both pressure and global heat stressors.
Thus, endothelial dysfunction, such as is commonly found in older people and people with diabetes, inhibits the endothelial cells from responding to multiple endothelial stressors. In a clinical setting, extra precautions must be taken with any type of thermal or compressive therapies done on patients with or at risk for endothelial dysfunction.
Doctor of Philosophy (PhD)
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Library of Congress/MESH Subject Headings
Endothelium, Vascular -- physiopathology; Aging -- physiology; Diabetis Mellitus -- physiopathology; Skin -- blood supply; Regional Blood Flow -- physiology; Blood Flow Velocity.
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This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.
McLellan, Katie, "Response of Endothelial Cells to Stressors: the Impact of Aging and Diabetes" (2008). Loma Linda University Electronic Theses, Dissertations & Projects. 1499.
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