The mechanisms and functional implications of altered microvascular vasoreactivity in healthy and essential hypertensive men and women
Open Access
- Author:
- Bruning, Rebecca S
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- November 11, 2013
- Committee Members:
- Lacy Marie Alexander, Dissertation Advisor/Co-Advisor
William Lawrence Kenney Jr., Committee Chair/Co-Chair
Nilam Ram, Committee Member
Timothy Mc Connell, Special Member - Keywords:
- nitric oxide
endothelial function
skin flowmotion
core temperature - Abstract:
- Cutaneous vasodilation enables nutrient delivery to the skin and effectively transfers heat away from the body core to the environment for thermoregulation. Cutaneous vasoreactivity is reflective of global changes in the microcirculation and endothelial function. The purpose of this series of studies was to investigate and characterize the mechanisms mediating cutaneous NO-dependent vasodilation in middle-aged and essential hypertensive men and women. In the first study we investigated the specific nitric oxide synthase (NOS) isoforms responsible for mediating NO-dependent vasodilation during local skin heating and acetylcholine (Ach) perfusion in healthy young and middle-aged men and women. We found that endothelial NOS (eNOS) mediates NO-dependent vasodilation during both local skin heating and Ach perfusion in young and middle-aged individuals. Further, healthy middle-aging results in mild functional deficits in NO-dependent vasodilation. In the second study we used fast Fourier transformations (FFT) to examine how essential hypertension (HTN) alters skin flowmotion after standardized local skin heating protocols versus age-matched normotensive men and women. We found that HTN results in altered neurogenic and NO-dependent control of skin flowmotion. Drug therapies that alter cutaneous vasoreactivity could have functional thermoregulatory consequences during heat stress. In the third study we examined the thermoregulatory and cardiovascular consequences of antithrombotic therapy (low dose aspirin, ASA) and clopidogrel bisulfate (Plavix®, CLO) during rest and exercise in a hot environment. We found that ASA and CLO elevate core temperatures during passive heat stress and shift the onset of peripheral thermoeffector mechanisms toward higher body temperatures during exercise in the heat.