Sympathetic control of reflex cutaneous vasoconstriction in human aging.
This Synthesis highlights a series of recent studies that has systematically interrogated age-related deficits in cold-induced skin vasoconstriction. In response to cold stress, a reflex increase in sympathetic nervous system activity mediates reductions in skin blood flow. Reflex vasoconstriction during cold exposure is markedly impaired in aged skin, contributing to the relative inability of healthy older adults to maintain core temperature during mild cold stress in the absence of appropriate behavioral thermoregulation. This compromised reflex cutaneous vasoconstriction in healthy aging can occur as a result of functional deficits at multiple points along the efferent sympathetic reflex axis, including blunted sympathetic outflow directed to the skin vasculature, reduced presynaptic neurotransmitter synthesis and/or release, and altered end-organ responsiveness at several loci, in addition to potential alterations in afferent thermoreceptor function. Arguments have been made that the relative inability of aged skin to appropriately constrict is due to the aging cutaneous arterioles themselves, whereas other data point to the neural circuitry controlling those vessels. The argument presented herein provides strong evidence for impaired efferent sympathetic control of the peripheral cutaneous vasculature during whole body cold exposure as the primary mechanism responsible for attenuated vasoconstriction.
Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania jlg52@psu.edu.
Jody L
JL
Greaney
Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania.
Lacy M
LM
Alexander
Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, Pennsylvania.
W Larry
WL
Kenney
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001833:Body Temperature Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012018:Reflex / Q000502:physiology*; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014661:Vasoconstriction / Q000502:physiology*
autonomic control; cold stress; hypothermia; skin blood flow