Abstract:
OBJECTIVE:High aerobic fitness may prevent age-related decrements in cutaneous vasodilation while type 2 diabetes may exacerbate this decline. The mechanisms underlying these responses remain unclear, but may be due to an excess of reactive oxygen species. We hypothesized that superoxide scavenging or NADPH oxidase inhibition would improve cutaneous vasodilation in older adults exercising in the heat, particularly in healthy low-fit individuals and those with type 2 diabetes. METHODS:Twenty seven older adults were evenly separated into three groups (healthy low-fit: VO2peak = 24.4 ± 2.4 ml·kg-1·min-1, 61 ± 8 years; healthy high-fit: 42.5 ± 9.7 ml·kg-1·min-1, 56 ± 6 years; type 2 diabetes: 30.0 ± 7.6, ml·kg-1·min-1, 58 ± 7 years). The healthy low-fit and type 2 diabetes groups performed two successive 30-min cycling bouts at 65%VO2peak in the heat (35°C), separated by 30-min rest. The high-fit group cycled at the same absolute heat load (and therefore requirement for heat loss) as their healthy low-fit counterparts during the first exercise bout (Ex1) and at the same relative intensity (65%VO2peak) during the second (Ex2). Forearm cutaneous vascular conductance (CVC%max) was measured at microdialysis sites perfused with: 1) lactated Ringer's solution (control); 2) 10 mM NG-nitro-L-arginine-methyl-ester (L-NAME, nitric oxide synthase inhibitor); 3) 100 μM apocynin (NADPH oxidase inhibitor); 4) 10 μM tempol (superoxide dismutase mimetic), with responses compared at baseline, end-Ex1, and end-Ex2. RESULTS:In all groups, L-NAME consistently reduced CVC%max relative to the other treatment sites by ~16-21% during Ex1 and by ~22-27% during Ex2 (all P < 0.05). Conversely, superoxide scavenging and NADPH oxidase inhibition did not influence CVC%max (all P > 0.05). CONCLUSION:Superoxide and NADPH oxidase do not modulate cutaneous vasodilation in healthy low- or high-fit older adults exercising in the heat, regardless of aerobic fitness level or relative exercise intensity employed, nor do they influence cutaneous vasodilation during an exercise-heat stress in those with type 2 diabetes. However, NOS remains an important modulator of cutaneous vasodilation during exercise in all groups.
journal_name
Microvasc Resjournal_title
Microvascular researchauthors
McGarr GW,Fujii N,McNeely BD,Hatam K,Nishiyasu T,Sigal RJ,Boulay P,Kenny GPdoi
10.1016/j.mvr.2019.103886subject
Has Abstractpub_date
2019-09-01 00:00:00pages
103886eissn
0026-2862issn
1095-9319pii
S0026-2862(19)30080-9journal_volume
125pub_type
杂志文章abstract::Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and...
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