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Effect of Chronic Lower Limb Heating on Cutaneous Microvascular Function in Aged Humans
Author(s) -
Romero Steven A.,
Gag Daniel,
Adams Amy,
Jaffery Manall,
Crandall Craig G.
Publication year - 2018
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.2018.32.1_supplement.722.31
Subject(s) - sodium nitroprusside , nitric oxide , medicine , vasodilation , blood flow , microdialysis , laser doppler velocimetry , anesthesia , central nervous system
Cutaneous microvascular function is reduced with advancing age. Recent evidence suggests that chronic local heating of a limb improves cutaneous microvascular function in young healthy humans through nitric oxide‐dependent mechanisms. However, exposure to chronic heating of limb has not been studied in aged adults. The purpose of this study was to test the hypothesis that chronic lower limb heating improves nitric oxide‐dependent vasodilation in the cutaneous microvasculature of aged adults. Six healthy aged adults (5 females; age 67 ± 4 years; height 164 ± 3 cm; weight 70 ± 18 kg; mean ± SD) were exposed to 8 weeks of chronic lower limb heating. Subjects immersed their lower limbs ~33 cm into a heated (~ 42°C) and circulated water bath 4 days per week, for 45 min per session. Before and after the 8‐week regimen, cutaneous blood flow (laser Doppler red blood cell flux) was measured in response to 39 °C heating of a discreet area of skin exposed to chronic heating with and without (control) intradermal microdialysis administration of the nitric oxide synthase inhibitor Nω‐nitro‐L‐arginine methyl ester hydrochloride (L‐NAME; 20 mM). Estimated maximal cutaneous blood flow was assessed in response to combined local heating to 43 °C and intradermal infusion of sodium nitroprusside (56 mM). Cutaneous vascular conductance (CVC) was calculated as red blood cell flux divided by mean arterial pressure and expressed as a percentage of maximal vasodilation (%CVC max ), where appropriate. Cutaneous vascular conductance during 39 °C local heating was unchanged following chronic heating (pre 78 ± 5 %CVC max vs. post 85 ± 7 %CVC max ; P = 0.2). Likewise, nitric oxide‐dependent vasodilation (calculated as the difference between control and L‐NAME sites) did not differ (pre 68 ± 3 % vs. post 64 ± 3 %; P = 0.3). Interestingly, maximal cutaneous vascular conductance increased after chronic heating (pre 1.8 ± 0.1 flux mmHg −1 vs. post 2.4 ± 0.2 flux mmHg −1 ; P < 0.05). Taken together, chronic lower limb heating does not improve nitric oxide‐dependent cutaneous microvascular function during a local thermal provocation in aged adults, an effect that may be superseded by vascular remodeling as maximal vasodilator capacity was increased after the 8‐week regimen. Support or Funding Information National Institutes of Health (GM‐068865 & GM‐117693) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .