Local metabolic hypothesis is not sufficient to explain coronary autoregulatory behavior

Alexander M. Kiel, Adam G. Goodwill, Hana E. Baker, Gregory M. Dick, Johnathan Tune

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The local metabolic hypothesis proposes that myocardial oxygen tension determines the degree of autoregulation by increasing the production of vasodilator metabolites as perfusion pressure is reduced. Thus, normal physiologic levels of coronary venous PO2, an index of myocardial oxygenation, are proposed to be required for effective autoregulation. The present study challenged this hypothesis through determination of coronary responses to changes in coronary perfusion pressure (CPP 140–40 mmHg) in open-chest swine in the absence (n = 7) and presence of euvolemic hemodilution (~ 50% reduction in hematocrit), with (n = 5) and without (n = 6) infusion of dobutamine to augment MVO2. Coronary venous PO2 decreased over similar ranges (~ 28–15 mmHg) as CPP was lowered from 140 to 40 mmHg in each of the groups. However, coronary venous PO2 was not associated with changes in coronary blood flow (r = − 0.11; P = 0.29) or autoregulatory gain (r = − 0.29; P = 0.12). Coronary zero-flow pressure (Pzf) was measured in 20 mmHg increments and determined to be directly related to vascular resistance (r = 0.71; P < 0.001). Further analysis demonstrated that changes in coronary blood flow remained minimal at Pzf > 20 mmHg, but progressively increased as Pzf decreased below this threshold value (r = 0.68; P < 0.001). Coronary Pzf was also positively correlated with autoregulatory gain (r = 0.43; P = 0.001). These findings support that coronary autoregulatory behavior is predominantly dependent on an adequate degree of underlying vasomotor tone, independent of normal myocardial oxygen tension.

Original languageEnglish (US)
Article number33
JournalBasic Research in Cardiology
Volume113
Issue number5
DOIs
StatePublished - Sep 1 2018

Fingerprint

Pressure
Homeostasis
Perfusion
Oxygen
Hemodilution
Dobutamine
Vasodilator Agents
Hematocrit
Vascular Resistance
Swine
Thorax
3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid

Keywords

  • Autoregulation
  • Coronary
  • Swine
  • Zero-flow pressure

ASJC Scopus subject areas

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

Cite this

Local metabolic hypothesis is not sufficient to explain coronary autoregulatory behavior. / Kiel, Alexander M.; Goodwill, Adam G.; Baker, Hana E.; Dick, Gregory M.; Tune, Johnathan.

In: Basic Research in Cardiology, Vol. 113, No. 5, 33, 01.09.2018.

Research output: Contribution to journalArticle

Kiel, Alexander M. ; Goodwill, Adam G. ; Baker, Hana E. ; Dick, Gregory M. ; Tune, Johnathan. / Local metabolic hypothesis is not sufficient to explain coronary autoregulatory behavior. In: Basic Research in Cardiology. 2018 ; Vol. 113, No. 5.
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