Decreased active vasodilator sensitivity in aged skin

William Lawrence Kenney, Jr., A. L. Morgan, W. B. Farquhar, E. M. Brooks, J. M. Pierzga, J. A. Derr

Research output: Contribution to journalArticle

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Abstract

Older men and women respond to local and reflex-mediated heat stress with an attenuated increase in cutaneous vascular conductance (CVC). This study was performed to test the hypothesis that an augmented or sustained noradrenergic vasoconstriction (VC) may play a role in this age-related difference. Fifteen young (22 ±1 yr) and 15 older (66 ±1 yr) men exercised at 50% peak oxygen uptake in a 36°C environment. Skin perfusion was monitored at two sites on the right forearm by laser-Doppler flowmetry: one site pretreated with bretylium tosylate (BT) to block the local release of norepinephrine and thus VC and an adjacent control site. Blockade of reflex VC was verified during whole body cooling using a water-perfused suit. CVC (perfusion divided by mean arterial pressure) at each site was reported as a percentage of the maximal CVC (%CVCmax) induced at the end of each experiment by prolonged local heating at 42°C. Neither age nor BT affected the %CVCraax (75-86%) attained at high core temperatures. During the early rise phase of CVC, the %CVCmaxchange in esophageal temperature (ATes) curve was shifted to the right in the older men (effective ATes associated with 50% CVC response for young, 0.22 ±0.04 and 0.39 ±0.04°C and for older, 0.73 ±0.04 and 0.85 ±0.04°C at control and BT sites, respectively). BT had no interactive effect on this age difference, suggesting a lack of involvement of the VC system in the attenuated CVC response of individuals over the age of 60 yr. Additionally, increases in skin vascular conductance were quantitatively compared by measuring increases in total forearm vascular conductance (FVC, restricted to the forearm skin under these conditions). After the initial ~0.2°C increase in Tes, FVC was 40-50% lower in the older men (P < 0.01) for the remainder of the exercise. Decreased active vasodilator sensitivity to increasing core temperature, coupled with structural limitations to vasodilation, appears to limit the cutaneous vascular response to exertional heat stress in older subjects.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume41
Issue number4
StatePublished - Dec 1 1997

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Vasodilator Agents
Blood Vessels
Bretylium Tosylate
Skin
Vasoconstriction
Forearm
Temperature
Reflex
Perfusion
Hot Temperature
Laser-Doppler Flowmetry
Vasodilation
Heating
Norepinephrine
Arterial Pressure
Exercise
Oxygen
Water

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Kenney, Jr., W. L., Morgan, A. L., Farquhar, W. B., Brooks, E. M., Pierzga, J. M., & Derr, J. A. (1997). Decreased active vasodilator sensitivity in aged skin. American Journal of Physiology - Heart and Circulatory Physiology, 41(4).
Kenney, Jr., William Lawrence ; Morgan, A. L. ; Farquhar, W. B. ; Brooks, E. M. ; Pierzga, J. M. ; Derr, J. A. / Decreased active vasodilator sensitivity in aged skin. In: American Journal of Physiology - Heart and Circulatory Physiology. 1997 ; Vol. 41, No. 4.
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abstract = "Older men and women respond to local and reflex-mediated heat stress with an attenuated increase in cutaneous vascular conductance (CVC). This study was performed to test the hypothesis that an augmented or sustained noradrenergic vasoconstriction (VC) may play a role in this age-related difference. Fifteen young (22 ±1 yr) and 15 older (66 ±1 yr) men exercised at 50{\%} peak oxygen uptake in a 36°C environment. Skin perfusion was monitored at two sites on the right forearm by laser-Doppler flowmetry: one site pretreated with bretylium tosylate (BT) to block the local release of norepinephrine and thus VC and an adjacent control site. Blockade of reflex VC was verified during whole body cooling using a water-perfused suit. CVC (perfusion divided by mean arterial pressure) at each site was reported as a percentage of the maximal CVC ({\%}CVCmax) induced at the end of each experiment by prolonged local heating at 42°C. Neither age nor BT affected the {\%}CVCraax (75-86{\%}) attained at high core temperatures. During the early rise phase of CVC, the {\%}CVCmaxchange in esophageal temperature (ATes) curve was shifted to the right in the older men (effective ATes associated with 50{\%} CVC response for young, 0.22 ±0.04 and 0.39 ±0.04°C and for older, 0.73 ±0.04 and 0.85 ±0.04°C at control and BT sites, respectively). BT had no interactive effect on this age difference, suggesting a lack of involvement of the VC system in the attenuated CVC response of individuals over the age of 60 yr. Additionally, increases in skin vascular conductance were quantitatively compared by measuring increases in total forearm vascular conductance (FVC, restricted to the forearm skin under these conditions). After the initial ~0.2°C increase in Tes, FVC was 40-50{\%} lower in the older men (P < 0.01) for the remainder of the exercise. Decreased active vasodilator sensitivity to increasing core temperature, coupled with structural limitations to vasodilation, appears to limit the cutaneous vascular response to exertional heat stress in older subjects.",
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Kenney, Jr., WL, Morgan, AL, Farquhar, WB, Brooks, EM, Pierzga, JM & Derr, JA 1997, 'Decreased active vasodilator sensitivity in aged skin', American Journal of Physiology - Heart and Circulatory Physiology, vol. 41, no. 4.

Decreased active vasodilator sensitivity in aged skin. / Kenney, Jr., William Lawrence; Morgan, A. L.; Farquhar, W. B.; Brooks, E. M.; Pierzga, J. M.; Derr, J. A.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 41, No. 4, 01.12.1997.

Research output: Contribution to journalArticle

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T1 - Decreased active vasodilator sensitivity in aged skin

AU - Kenney, Jr., William Lawrence

AU - Morgan, A. L.

AU - Farquhar, W. B.

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N2 - Older men and women respond to local and reflex-mediated heat stress with an attenuated increase in cutaneous vascular conductance (CVC). This study was performed to test the hypothesis that an augmented or sustained noradrenergic vasoconstriction (VC) may play a role in this age-related difference. Fifteen young (22 ±1 yr) and 15 older (66 ±1 yr) men exercised at 50% peak oxygen uptake in a 36°C environment. Skin perfusion was monitored at two sites on the right forearm by laser-Doppler flowmetry: one site pretreated with bretylium tosylate (BT) to block the local release of norepinephrine and thus VC and an adjacent control site. Blockade of reflex VC was verified during whole body cooling using a water-perfused suit. CVC (perfusion divided by mean arterial pressure) at each site was reported as a percentage of the maximal CVC (%CVCmax) induced at the end of each experiment by prolonged local heating at 42°C. Neither age nor BT affected the %CVCraax (75-86%) attained at high core temperatures. During the early rise phase of CVC, the %CVCmaxchange in esophageal temperature (ATes) curve was shifted to the right in the older men (effective ATes associated with 50% CVC response for young, 0.22 ±0.04 and 0.39 ±0.04°C and for older, 0.73 ±0.04 and 0.85 ±0.04°C at control and BT sites, respectively). BT had no interactive effect on this age difference, suggesting a lack of involvement of the VC system in the attenuated CVC response of individuals over the age of 60 yr. Additionally, increases in skin vascular conductance were quantitatively compared by measuring increases in total forearm vascular conductance (FVC, restricted to the forearm skin under these conditions). After the initial ~0.2°C increase in Tes, FVC was 40-50% lower in the older men (P < 0.01) for the remainder of the exercise. Decreased active vasodilator sensitivity to increasing core temperature, coupled with structural limitations to vasodilation, appears to limit the cutaneous vascular response to exertional heat stress in older subjects.

AB - Older men and women respond to local and reflex-mediated heat stress with an attenuated increase in cutaneous vascular conductance (CVC). This study was performed to test the hypothesis that an augmented or sustained noradrenergic vasoconstriction (VC) may play a role in this age-related difference. Fifteen young (22 ±1 yr) and 15 older (66 ±1 yr) men exercised at 50% peak oxygen uptake in a 36°C environment. Skin perfusion was monitored at two sites on the right forearm by laser-Doppler flowmetry: one site pretreated with bretylium tosylate (BT) to block the local release of norepinephrine and thus VC and an adjacent control site. Blockade of reflex VC was verified during whole body cooling using a water-perfused suit. CVC (perfusion divided by mean arterial pressure) at each site was reported as a percentage of the maximal CVC (%CVCmax) induced at the end of each experiment by prolonged local heating at 42°C. Neither age nor BT affected the %CVCraax (75-86%) attained at high core temperatures. During the early rise phase of CVC, the %CVCmaxchange in esophageal temperature (ATes) curve was shifted to the right in the older men (effective ATes associated with 50% CVC response for young, 0.22 ±0.04 and 0.39 ±0.04°C and for older, 0.73 ±0.04 and 0.85 ±0.04°C at control and BT sites, respectively). BT had no interactive effect on this age difference, suggesting a lack of involvement of the VC system in the attenuated CVC response of individuals over the age of 60 yr. Additionally, increases in skin vascular conductance were quantitatively compared by measuring increases in total forearm vascular conductance (FVC, restricted to the forearm skin under these conditions). After the initial ~0.2°C increase in Tes, FVC was 40-50% lower in the older men (P < 0.01) for the remainder of the exercise. Decreased active vasodilator sensitivity to increasing core temperature, coupled with structural limitations to vasodilation, appears to limit the cutaneous vascular response to exertional heat stress in older subjects.

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