CONTEXT: Nitric Oxide (NO) is an endothelial-derived vasoactive molecule that causes an increase in blood flow and oxygen delivery to tissue. A reduction in NO bioavailability has been found to occur in adults over the age of 60 and can be reversed pharmacologically by improving NO synthase (NOS) activity. Reversing these age-related changes with alternative interventions, such as aerobic exercise, has shown some promising results. OBJECTIVE: To quantify blood NO-bioavailability (as measured by blood nitrite levels) in a population of aerobically trained elderly men and compare these data to a group of age-matched, inactive individuals. In addition, we measured the cutaneous vasodilator response to local skin heating as a bioassay for NO-mediated cutaneous dilation. SETTING: BYU Human Performance Research Center (HPRC). PARTICIPANTS: 16 healthy elderly men (age = 66 ± 7.07 years) were divided into two groups based on physical fitness levels and estimated VO2max in ml O2•kg-1•min-1 (Trained = 39.1 ± 1.21, Untrained = 29.0 ± 2.70). INTERVENTIONS: A blood sample was collected and analyzed for NO. A microdialysis study was performed and dialysate was collected at 32°C and at 42°C. During the heating process, skin blood flow (skin vasomotor activity) was monitored and reported as cutaneous vascular conductance (CVC). MAIN OUTCOME MEASURES: Whole blood nitrite concentrations, pre- and post-heat nitrite concentrations, and CVCmax were compared between trained and untrained groups. RESULTS: Whole blood nitrite concentration was similar in trained subjects and untrained subjects averaging 25.77 ± 6.75 and 21.43 ± 7.20 µM, respectively (F1,13 = 0.19; P = 0.6671]. Local skin heating had no impact on the concentration of nitrite in dialysate samples ([NOx]dialysate F1,26 = 0.01; P = 0.7567). In addition, the plateau in % CVCmax following 30 minutes of local heating was similar for trained and untrained subjects averaging 67.7 ± 5.8 and 68.0 ± 6.2 % CVCmax, respectively (F1,13 = 0.00; P = 0.9673). CONCLUSIONS: The results of this study indicate that age-mediated reductions in whole blood NO-bioavailability and decrements in NO-mediated cutaneous vasodilation during local heating were similar in aerobically fit and sedentary adults 60 years old or older. We conclude that a commitment to aerobic fitness was unable to overcome the age-related dysfunction of the NOS system.
College and Department
Life Sciences; Exercise Sciences
BYU ScholarsArchive Citation
Burton, Samantha, "The Effect of Aerobic Exercise Versus Inactivity on Nitric Oxide Concentration and Synthesis in an Elderly Population" (2015). Theses and Dissertations. 6140.
microdialysis, skin vasomotor activity, cutaneous vascular conductance