Quantitative analysis of feedforward sympathetic coronary vasodilation in exercising dogs

M. W. Gorman, Johnathan Tune, K. N. Richmond, E. O. Feigl

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Recent experiments demonstrate that feedforward sympathetic β-adrenoceptor coronary vasodilation occurs during exercise. The present study quantitatively examined the contributions of epinephrine and norepinephrine to exercise coronary hyperemia and tested the hypothesis that circulating epinephrine causes feedforward β-receptor-mediated coronary dilation. Dogs (n = 10) were chronically instrumented with a circumflex coronary artery flow transducer and catheters in the aorta and coronary sinus. During strenuous treadmill exercise, myocardial oxygen consumption increased by ~3.9-fold, coronary blood flow increased by ~3.6-fold, and arterial plasma epinephrine concentration increased by ~2.4-fold over resting levels. At arterial concentrations matching those during strenuous exercise, epinephrine infused at rest (n = 6) produced modest increases (18%) in flow and myocardial oxygen consumption but no evidence of direct β-adrenoceptor-mediated coronary vasodilation. Arterial norepinephrine concentration increased by ~5.4-fold during exercise, and coronary venous norepinephrine was always higher than arterial, indicating norepinephrine release from cardiac sympathetic nerves. With the use of a mathematical model of cardiac capillary norepinephrine transport, these norepinephrine concentrations predict an average interstitial norepinephrine concentration of ~12 nM during strenuous exercise. Published dose-response data indicate that this norepinephrine concentration increases isolated coronary arteriolar conductance by ~67%, which can account for ~25% of the increase in flow observed during exercise. It is concluded that a significant portion of coronary exercise hyperemia (~25%) can be accounted for by direct feedforward β-adrenoceptor coronary vascular effects of norepinephrine, with little effect from circulating epinephrine.

Original languageEnglish (US)
Pages (from-to)1903-1911
Number of pages9
JournalJournal of Applied Physiology
Volume89
Issue number5
StatePublished - 2000
Externally publishedYes

Fingerprint

Vasodilation
Norepinephrine
Dogs
Epinephrine
Adrenergic Receptors
Hyperemia
Oxygen Consumption
Coronary Sinus
Transducers
Blood Vessels
Aorta
Dilatation
Coronary Vessels
Theoretical Models
Catheters

Keywords

  • Coronary blood flow
  • Epinephrine
  • Norepinephrine

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Quantitative analysis of feedforward sympathetic coronary vasodilation in exercising dogs. / Gorman, M. W.; Tune, Johnathan; Richmond, K. N.; Feigl, E. O.

In: Journal of Applied Physiology, Vol. 89, No. 5, 2000, p. 1903-1911.

Research output: Contribution to journalArticle

Gorman, M. W. ; Tune, Johnathan ; Richmond, K. N. ; Feigl, E. O. / Quantitative analysis of feedforward sympathetic coronary vasodilation in exercising dogs. In: Journal of Applied Physiology. 2000 ; Vol. 89, No. 5. pp. 1903-1911.
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