Mechanisms of acetylcholine-mediated vasodilation in young and aged human skin

Lacy Marie Alexander, Caitlin S. Thompson, Christopher T. Minson, William Lawrence Kenney, Jr.

Research output: Contribution to journalArticle

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Abstract

Thermoregulatory cutaneous vasodilatation (VD) is attenuated in aged skin. While acetylcholine (ACh) plays a role in thermally mediated VD, the precise mechanisms through which ACh-mediated VD acts and whether those downstream mechanisms change with ageing are unclear. We tested the hypotheses that both nitric oxide (NO)- and prostanoid-mediated pathways contribute to exogenous ACh-mediated VD, and that both are attenuated with advanced age. Twelve young (Y: 23 ± 1 years) and 10 older (O: 69 ± 1 years) subjects underwent infusions of 137.5 μM ACh at four intradermal microdialysis sites: control (C, Ringer solution), NO synthase inhibited (NOS-I, 10 mM L-NAME), cyclooxygenase inhibited (COX-I, 10 mM ketorolac) and NOS-I + COX-I. Red blood cell flux was monitored using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated (laser-Doppler flux/mean arterial pressure) and normalized to maximal CVC (%CVCmax) (28 mM sodium nitroprusside + local heating to 43°C). Baseline %CVCmax was increased in the O at COX-I sites (COX-I 16 ± 1, NOS-I + COX-I 16 ± 2 versus C 10 ± 1%CVCmax; P < 0.001) but not in the young, suggesting an age-related shift toward COX vasoconstrictors contributing to basal cutaneous vasomotor tone. There was no difference in peak %CVCmax during ACh infusion between age groups, and the response was unchanged by NOS-I (O: NOS-I 35 ± 5 versus C 38 ± 5%CVCmax; P = 0.84) (Y: NOS-I 41 ± 4 versus C 39 ± 4%CVCmax; P = 0.67). COX-I and NOS-I + COX-I attenuated the peak CVC response to ACh in both groups (COX-I O: 29 ± 3, Y: 22 ± 2%CVCmax versus C; P < 0.001 both groups; NOS-I + COX-I O: 32 ± 3 versus Y: 29 ± 2%CVCmax; versus C; P < 0.001 both groups). ACh mediates cutaneous VD through prostanoid and non-NO-, non-prostanoid-dependent pathways. Further, older subjects have a diminished prostanoid contribution to ACh-mediated VD.

Original languageEnglish (US)
Pages (from-to)965-973
Number of pages9
JournalJournal of Physiology
Volume563
Issue number3
DOIs
StatePublished - Mar 15 2005

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Vasodilation
Acetylcholine
Skin
Prostaglandins
Blood Vessels
Ketorolac
Skin Pigmentation
Laser-Doppler Flowmetry
NG-Nitroarginine Methyl Ester
Microdialysis
Nitroprusside
Vasoconstrictor Agents
Prostaglandin-Endoperoxide Synthases
Nitric Oxide Synthase
Heating
Oxides
Arterial Pressure
Nitric Oxide
Lasers
Age Groups

All Science Journal Classification (ASJC) codes

  • Physiology

Cite this

@article{6ea4aec8d50e4c7589dbb7a8b061cadd,
title = "Mechanisms of acetylcholine-mediated vasodilation in young and aged human skin",
abstract = "Thermoregulatory cutaneous vasodilatation (VD) is attenuated in aged skin. While acetylcholine (ACh) plays a role in thermally mediated VD, the precise mechanisms through which ACh-mediated VD acts and whether those downstream mechanisms change with ageing are unclear. We tested the hypotheses that both nitric oxide (NO)- and prostanoid-mediated pathways contribute to exogenous ACh-mediated VD, and that both are attenuated with advanced age. Twelve young (Y: 23 ± 1 years) and 10 older (O: 69 ± 1 years) subjects underwent infusions of 137.5 μM ACh at four intradermal microdialysis sites: control (C, Ringer solution), NO synthase inhibited (NOS-I, 10 mM L-NAME), cyclooxygenase inhibited (COX-I, 10 mM ketorolac) and NOS-I + COX-I. Red blood cell flux was monitored using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated (laser-Doppler flux/mean arterial pressure) and normalized to maximal CVC ({\%}CVCmax) (28 mM sodium nitroprusside + local heating to 43°C). Baseline {\%}CVCmax was increased in the O at COX-I sites (COX-I 16 ± 1, NOS-I + COX-I 16 ± 2 versus C 10 ± 1{\%}CVCmax; P < 0.001) but not in the young, suggesting an age-related shift toward COX vasoconstrictors contributing to basal cutaneous vasomotor tone. There was no difference in peak {\%}CVCmax during ACh infusion between age groups, and the response was unchanged by NOS-I (O: NOS-I 35 ± 5 versus C 38 ± 5{\%}CVCmax; P = 0.84) (Y: NOS-I 41 ± 4 versus C 39 ± 4{\%}CVCmax; P = 0.67). COX-I and NOS-I + COX-I attenuated the peak CVC response to ACh in both groups (COX-I O: 29 ± 3, Y: 22 ± 2{\%}CVCmax versus C; P < 0.001 both groups; NOS-I + COX-I O: 32 ± 3 versus Y: 29 ± 2{\%}CVCmax; versus C; P < 0.001 both groups). ACh mediates cutaneous VD through prostanoid and non-NO-, non-prostanoid-dependent pathways. Further, older subjects have a diminished prostanoid contribution to ACh-mediated VD.",
author = "Alexander, {Lacy Marie} and Thompson, {Caitlin S.} and Minson, {Christopher T.} and {Kenney, Jr.}, {William Lawrence}",
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Mechanisms of acetylcholine-mediated vasodilation in young and aged human skin. / Alexander, Lacy Marie; Thompson, Caitlin S.; Minson, Christopher T.; Kenney, Jr., William Lawrence.

In: Journal of Physiology, Vol. 563, No. 3, 15.03.2005, p. 965-973.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Mechanisms of acetylcholine-mediated vasodilation in young and aged human skin

AU - Alexander, Lacy Marie

AU - Thompson, Caitlin S.

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AU - Kenney, Jr., William Lawrence

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N2 - Thermoregulatory cutaneous vasodilatation (VD) is attenuated in aged skin. While acetylcholine (ACh) plays a role in thermally mediated VD, the precise mechanisms through which ACh-mediated VD acts and whether those downstream mechanisms change with ageing are unclear. We tested the hypotheses that both nitric oxide (NO)- and prostanoid-mediated pathways contribute to exogenous ACh-mediated VD, and that both are attenuated with advanced age. Twelve young (Y: 23 ± 1 years) and 10 older (O: 69 ± 1 years) subjects underwent infusions of 137.5 μM ACh at four intradermal microdialysis sites: control (C, Ringer solution), NO synthase inhibited (NOS-I, 10 mM L-NAME), cyclooxygenase inhibited (COX-I, 10 mM ketorolac) and NOS-I + COX-I. Red blood cell flux was monitored using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated (laser-Doppler flux/mean arterial pressure) and normalized to maximal CVC (%CVCmax) (28 mM sodium nitroprusside + local heating to 43°C). Baseline %CVCmax was increased in the O at COX-I sites (COX-I 16 ± 1, NOS-I + COX-I 16 ± 2 versus C 10 ± 1%CVCmax; P < 0.001) but not in the young, suggesting an age-related shift toward COX vasoconstrictors contributing to basal cutaneous vasomotor tone. There was no difference in peak %CVCmax during ACh infusion between age groups, and the response was unchanged by NOS-I (O: NOS-I 35 ± 5 versus C 38 ± 5%CVCmax; P = 0.84) (Y: NOS-I 41 ± 4 versus C 39 ± 4%CVCmax; P = 0.67). COX-I and NOS-I + COX-I attenuated the peak CVC response to ACh in both groups (COX-I O: 29 ± 3, Y: 22 ± 2%CVCmax versus C; P < 0.001 both groups; NOS-I + COX-I O: 32 ± 3 versus Y: 29 ± 2%CVCmax; versus C; P < 0.001 both groups). ACh mediates cutaneous VD through prostanoid and non-NO-, non-prostanoid-dependent pathways. Further, older subjects have a diminished prostanoid contribution to ACh-mediated VD.

AB - Thermoregulatory cutaneous vasodilatation (VD) is attenuated in aged skin. While acetylcholine (ACh) plays a role in thermally mediated VD, the precise mechanisms through which ACh-mediated VD acts and whether those downstream mechanisms change with ageing are unclear. We tested the hypotheses that both nitric oxide (NO)- and prostanoid-mediated pathways contribute to exogenous ACh-mediated VD, and that both are attenuated with advanced age. Twelve young (Y: 23 ± 1 years) and 10 older (O: 69 ± 1 years) subjects underwent infusions of 137.5 μM ACh at four intradermal microdialysis sites: control (C, Ringer solution), NO synthase inhibited (NOS-I, 10 mM L-NAME), cyclooxygenase inhibited (COX-I, 10 mM ketorolac) and NOS-I + COX-I. Red blood cell flux was monitored using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated (laser-Doppler flux/mean arterial pressure) and normalized to maximal CVC (%CVCmax) (28 mM sodium nitroprusside + local heating to 43°C). Baseline %CVCmax was increased in the O at COX-I sites (COX-I 16 ± 1, NOS-I + COX-I 16 ± 2 versus C 10 ± 1%CVCmax; P < 0.001) but not in the young, suggesting an age-related shift toward COX vasoconstrictors contributing to basal cutaneous vasomotor tone. There was no difference in peak %CVCmax during ACh infusion between age groups, and the response was unchanged by NOS-I (O: NOS-I 35 ± 5 versus C 38 ± 5%CVCmax; P = 0.84) (Y: NOS-I 41 ± 4 versus C 39 ± 4%CVCmax; P = 0.67). COX-I and NOS-I + COX-I attenuated the peak CVC response to ACh in both groups (COX-I O: 29 ± 3, Y: 22 ± 2%CVCmax versus C; P < 0.001 both groups; NOS-I + COX-I O: 32 ± 3 versus Y: 29 ± 2%CVCmax; versus C; P < 0.001 both groups). ACh mediates cutaneous VD through prostanoid and non-NO-, non-prostanoid-dependent pathways. Further, older subjects have a diminished prostanoid contribution to ACh-mediated VD.

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