Healthy active older adults have enhanced K+channel-dependent endothelial vasodilatory mechanisms

American Journal of Physiology - Regulatory Integrative and Comparative Physiology - Tập 319 Số 1 - Trang R19-R25 - 2020
Corinna Serviente1,2, Craig W. Berry2, W. Larry Kenney1,2, Lacy M. Alexander1,2
1Center for Healthy Aging, Pennsylvania State University, University Park, Pennsylvania
2Department of Kinesiology, Pennsylvania State University, University Park, Pennsylvania

Tóm tắt

Microvascular endothelial dysfunction, a precursor to atherosclerotic cardiovascular disease, increases with aging. Endothelium-derived hyperpolarizing factors (EDHFs), which act through K+channels, regulate blood flow and are important to vascular health. It is unclear how EDHFs change with healthy aging. To evaluate microvascular endothelial reliance on K+channel-mediated dilation as a function of age in healthy humans. Microvascular function was assessed using intradermal microdialysis in healthy younger (Y; n = 7; 3 M/4 W; 26 ± 1 yr) and older adults (O; n = 12; 5 M/7 W; 64 ± 2 yr) matched for V̇o2peak(Y: 39.0 ± 3.8, O: 37.6 ± 3.1 mL·kg−1·min−1). Participants underwent graded local infusions of: the K+channel activator Na2S (10−6to 10−1M), acetylcholine (ACh, 10−10to 10−1M), ACh + the K+channel inhibitor tetraethylammonium (TEA; 25 or 50 mM), and ACh + the nitric oxide synthase-inhibitor l-NAME (15 mM). Red blood cell flux was measured with laser-Doppler flowmetry and used to calculate cutaneous vascular conductance (CVC; flux/mean arterial pressure) as a percentage of each site-specific maximum (%CVCmax, 43°C+28 mM sodium nitroprusside). The %CVCmaxresponse to Na2S was higher in older adults (mean, O: 51.7 ± 3.9% vs. Y: 36.1 ± 5.3%; P = 0.03). %CVCmaxwas lower in the ACh+TEA vs. the ACh site starting at 10−5M (ACh: 34.0 ± 5.7% vs. ACh+TEA: 19.4 ± 4.5%; P = 0.002) in older and at 10−4M (ACh: 54.5 ± 9.4% vs. ACh+TEA: 31.2 ± 6.7%; P = 0.0002) in younger adults. %CVCmaxwas lower in the ACh+l-NAME vs. the ACh site in both groups starting at 10−4M ACh (Y: P < 0.001; O: P = 0.02). Healthy active older adults have enhanced K+channel-dependent endothelial vasodilatory mechanisms, suggesting increased responsiveness to EDHFs with age.

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American Journal of Physiology - Regulatory Integrative and Comparative Physiology

Tập 319 Số 1

R19-R25

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