Nitric Oxide Dependence Calculations: Determining Nitric Oxide Contributions for 39°C and 42°C Local Heating Protocols
Open Access
- Author:
- Erdal, Melisa
- Area of Honors:
- Kinesiology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Lacy Marie Alexander, Thesis Supervisor
Lacy Marie Alexander, Thesis Honors Advisor
William E Buckley, Faculty Reader - Keywords:
- endothelial microvascular function
local heating
skin blood flow
nitric oxide
microdialysis
laser-Doppler flowmetry
Vasoconstriction
Vasodilation
nitric oxide mediated vasodilation
endothelial microvascular function
local heating
skin blood flow
nitric oxide
microdialysis
laser-Doppler flowmetry
vasoconstriction
vasodilation
nitric oxide mediated vasodilation - Abstract:
- Endothelial microvascular function of skin blood vessels is predictive of the cardiovascular disease risk (Holowatz et al., 2008). This study aims to examine differences in nitric oxide- (NO) dependent vasodilation during 39°C and 42°C local heating protocols and determine if the method of calculating NO contribution influences findings. We hypothesized that NO would contribute more to vasodilation when the skin blood flow (SkBF) values are subtracted (traditional) rather than the contribution value calculated from the percent change (relative). In addition, we hypothesized that older subjects would have reduced NO-dependent vasodilation in both protocols and with both methods of analysis. We conducted a cross-sectional study of 31 young (12 male/19 female, 24 (4) years) and 18 older (5 male/13 female, 68 (7.517)) participants. NO-dependent vasodilation was determined by perfusing (intradermal microdialysis) 15 nM N-nitro-l-arginine methyl ester during the heating plateau of the 39°C and 42°C protocols. Red blood cell flux (laser-Doppler flowmetry) was used to calculate cutaneous vascular conductance (CVC; red blood cell flux/mean arterial pressure), and values were represented as a percentage of maximum (%CVCmax) (28 nM sodium nitroprusside + 43°C). We found that when NO contribution is analyzed with the traditional method, NO contribution was lower in the older group than the young group in the 39°C heating protocol (p=0.030) but not in the 42°C protocol (p=0.262). We also found that NO contribution was lower in the 39°C protocol in the older group (p<0.001), but there were no differences in protocols in the younger group (p=0.967). When NO contribution is analyzed with the relative method, there were no age-related differences for the 39°C heating protocol (p=0.339). We also found that the NO contribution was lower in the 39°C protocol compared to the 42°C for the older group (p=0.039). In conclusion, age-related and protocol-related responses to local heating depend on how responses are analyzed.