Feedforward sympathetic coronary vasodilation in exercising dogs

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

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

The hypothesis that exercise-induced coronary vasodilation is a result of sympathetic activation of coronary smooth muscle β-adrenoceptors was tested. Ten dogs were chronically instrumented with a flow transducer on the circumflex coronary artery and catheters in the aorta and coronary sinus. During treadmill exercise, coronary venous oxygen tension decreased with increasing myocardial oxygen consumption, indicating an imperfect match between myocardial blood flow and oxygen consumption. This match was improved after α-adrenoceptor blockade with phentolamine but was significantly worse than control after α + β-adrenoceptor blockade with phentolamine plus propranolol. The response after α-adrenoceptor blockade included local metabolic vasodilation plus a β-adrenoceptor vasodilator component, whereas the response after α + β-adrenoceptor blockade contained only the local metabolic vasodilator component. The large difference in coronary venous oxygen tensions during exercise between α-adrenoceptor blockade and α + β-adrenoceptor blockade indicates that there is significant feedforward β-adrenoceptor coronary vasodilation in exercising dogs. Coronary venous and estimated myocardial interstitial adenosine concentrations did not increase during exercise before or after α + β-adrenoceptor blockade, indicating that adenosine levels did not increase to compensate for the loss of feedforward β-adrenoceptor-mediated coronary vasodilation. These results indicate a meaningful role for feedforward β-receptor-mediated sympathetic coronary vasodilation during exercise.

Original languageEnglish (US)
Pages (from-to)1892-1902
Number of pages11
JournalJournal of Applied Physiology
Volume89
Issue number5
StatePublished - 2000
Externally publishedYes

Fingerprint

Vasodilation
Adrenergic Receptors
Dogs
Phentolamine
Vasodilator Agents
Oxygen Consumption
Adenosine
Oxygen
Coronary Sinus
Transducers
Propranolol
Smooth Muscle
Aorta
Coronary Vessels
Catheters

Keywords

  • Adenosine
  • Coronary blood flow
  • Feedback control
  • Norepinephrine

ASJC Scopus subject areas

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

Cite this

Gorman, M. W., Tune, J., Richmond, K. N., & Feigl, E. O. (2000). Feedforward sympathetic coronary vasodilation in exercising dogs. Journal of Applied Physiology, 89(5), 1892-1902.

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. 1892-1902.

Research output: Contribution to journalArticle

Gorman, MW, Tune, J, Richmond, KN & Feigl, EO 2000, 'Feedforward sympathetic coronary vasodilation in exercising dogs', Journal of Applied Physiology, vol. 89, no. 5, pp. 1892-1902.
Gorman, M. W. ; Tune, Johnathan ; Richmond, K. N. ; Feigl, E. O. / Feedforward sympathetic coronary vasodilation in exercising dogs. In: Journal of Applied Physiology. 2000 ; Vol. 89, No. 5. pp. 1892-1902.
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