Comparison of brachial dilatory responses to hypercapnia and reactive hyperemia

Justin R. Geijer, Neil E. Hultgren, Nicholas G Evanoff, Aaron S Kelly, Michael A. Chernin, Matthew G. Stoltman, Donald R Dengel

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Flow-mediated dilation (FMD) relies on reactive hyperemia to stimulate the endothelium to release nitric oxide, causing smooth muscle relaxation. Hypercapnia also produces vasodilation, which is thought to be nitric oxide-independent. The purpose of this study was to compare and contrast the effects of hypercapnia and reactive hyperemia as stimuli for brachial artery dilation. On separate days, twenty-five participants underwent vasodilation studies via reactive hyperemia or hypercapnia (i.e. 10 mmHg increase in end-tidal carbon dioxide [PetCO2)]). During both studies changes in brachial artery diameter were recorded using continuous ultrasound imaging. Heart rate (HR) was measured throughout both tests. Resting HR (63 ± 11 versus 68 ± 14 beats min-1, p = 0.0027) and baseline brachial artery diameter measurements (4.57 ± 1.51 versus 5.28 ± 1.86 mm, p = 0.022) were significantly different between reactive hyperemia and hypercapnia, respectively. HR at peak dilation (65 ± 11 versus 76 ± 14 beats min-1, p < 0.0001), peak vessel dilation (8.68 ± 4.50 versus 5.28 ± 1.86%, p = 0.002), and time to peak dilation (90.8 ± 120.1 versus 658.3 ± 226.6 s, p < 0.0001) were also significantly different between reactive hyperemia and hypercapnia. The dynamics by which reactive hyperemia and hypercapnia stimulate vasodilation appear to differ. Hypercapnia produces a smaller and slower vasodilatory effect than reactive hyperemia. Further research is necessary to better understand the mechanisms of vasodilation under hypercapnic conditions.

Original languageEnglish (US)
Article number380
Pages (from-to)380-386
Number of pages7
JournalPhysiological Measurement
Volume37
Issue number3
DOIs
StatePublished - Feb 10 2016

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Hypercapnia
Hyperemia
Arm
Dilatation
Nitric oxide
Vasodilation
Brachial Artery
Heart Rate
Nitric Oxide
Muscle
Carbon dioxide
Ultrasonics
Muscle Relaxation
Imaging techniques
Carbon Dioxide
Endothelium
Smooth Muscle
Ultrasonography
Research

Keywords

  • flow mediated dilation
  • hypercapnia
  • PCO
  • reactive hyperemia
  • ultrasound

Cite this

Comparison of brachial dilatory responses to hypercapnia and reactive hyperemia. / Geijer, Justin R.; Hultgren, Neil E.; Evanoff, Nicholas G; Kelly, Aaron S; Chernin, Michael A.; Stoltman, Matthew G.; Dengel, Donald R.

In: Physiological Measurement, Vol. 37, No. 3, 380, 10.02.2016, p. 380-386.

Research output: Contribution to journalArticle

Geijer, Justin R. ; Hultgren, Neil E. ; Evanoff, Nicholas G ; Kelly, Aaron S ; Chernin, Michael A. ; Stoltman, Matthew G. ; Dengel, Donald R. / Comparison of brachial dilatory responses to hypercapnia and reactive hyperemia. In: Physiological Measurement. 2016 ; Vol. 37, No. 3. pp. 380-386.
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