Premium
Blunted Increases in Skin Sympathetic Nerve Activity Contribute to the Attenuated Reflex Vasodilation in Aged Human Skin
Author(s) -
Stanhewicz Anna E,
Greaney Jody L,
Alexander Lacy M,
Kenney W. Larry
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1290.1
Subject(s) - microneurography , vasodilation , reflex , medicine , dermatome , vasoconstriction , thermoregulation , anesthesia , human skin , endocrinology , blood pressure , baroreflex , heart rate , biology , genetics
When core and skin temperatures are elevated, reflex cutaneous vasodilation is attenuated in human aging, even in the absence of overt cardiovascular disease or elevated cardiovascular disease risk factors. This diminished response is mediated, in part, by age‐associated alterations in endothelial function; however the relative contribution of altered skin sympathetic nervous system activity (SSNA) remains unclear. We hypothesized that 1) apparently healthy older (O) adults would demonstrate blunted SSNA responses to increased core temperature compared to young (Y) adults, and 2) that the decreased SSNA response would be associated with an attenuated cutaneous vasodilation. Reflex vasodilation was induced in 8 Y (24 ± 1 yrs; range = 20–29 yrs) and 8 O (68 ± 2 yrs; range = 60–79 yrs) adults using a water‐perfused suit to elevate esophageal temperature (T es ) by 1.0°C. SSNA (peroneal microneurography) and red cell flux (laser Doppler flowmetry) in the innervated dermatome (the dorsum of foot) were continuously measured. SSNA was normalized to, and expressed as, a percentage of baseline. Cutaneous vascular conductance (CVC) was calculated as flux/mean arterial pressure and expressed as a percentage of maximal CVC (local heating to 43°C). Reflex vasodilation was attenuated in O adults (O: 26±3 vs. Y: 56 ± 5 %CVCmax; p<0.001). During whole‐body heating, SSNA increased in both groups (p<0.05); however, the response was significantly blunted in O adults (O: Δ265 ± 79 vs. Y: Δ593 ± 73%; p=0.006). The increase in SSNA during heating was significantly correlated with cutaneous vasodilation in both Y (r 2 = 0.97, p<0.001) and O (r 2 = 0.92, p<0.001) adults throughout heating, with no age‐related differences in the slope of the linear regression between SSNA and %CVCmax (O: 0.06 ± 0.01 vs. Y: 0.07 ± 0.00; NS). These data demonstrate that age‐related impairments in reflex cutaneous vasodilation are mediated, in part, by a blunted efferent SSNA during hyperthermia. Support or Funding Information ACSM Research Endowment Grant