What does this research mean for the field?

Sympathetic alpha receptor-mediated coronary vasoconstriction operates during coronary stenosis to limit oxygen delivery and increase myocardial oxygen extraction, though without causing net myocardial lactate production. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To determine whether sympathetic alpha receptor-mediated coronary vasoconstriction competes with metabolic vasodilation in the presence of coronary stenosis.

March 1, 1981Circulation Research

Adrenergic coronary vasoconstriction in the presence of coronary stenosis in the dog.

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Why the study?

Does alpha receptor blockade with phenoxybenzamine prevent sympathetic alpha receptor-mediated coronary vasoconstriction during norepinephrine infusion in dogs with coronary stenosis?

Population

Closed-chest dogs with left coronary artery cannulated and blood flow restricted by a moderate stenosis

Comparison

Intracoronary norepinephrine infusion following… vs Intracoronary norepinephrine infusion with alpha…

Design

Preclinical

Authors

CBCharles W. BuffingtonUniversity of Pittsburgh Medical Center EFEric O. FeiglUniversitat Autònoma de Barcelona

Discussion

Member takes

Implication

Alpha receptor blockade may attenuate coronary vasoconstriction during sympathetic activation with stenosis; leaves open relevance to human CAD.

Key Points

To determine whether sympathetic alpha receptor-mediated coronary vasoconstriction competes with metabolic vasodilation in the presence of coronary stenosis.
Cannulated the left coronary artery in closed-chest dogs and induced a moderate stenosis with a 70% area reduction.
Infused intracoronary norepinephrine to activate vascular alpha and myocardial beta receptors before and after alpha-receptor blockade with intracoronary phenoxybenzamine (0.25 mg/kg).
Measured coronary vascular resistance, myocardial oxygen and lactate extraction, and coronary sinus oxygen tension across matching levels of myocardial oxygen consumption.
In the presence of stenosis, intracoronary norepinephrine decreased coronary sinus oxygen content and increased myocardial oxygen extraction.
At equivalent levels of myocardial oxygen consumption, coronary vascular resistance was significantly greater with intact alpha receptors than after phenoxybenzamine blockade, which eliminated the increase in oxygen extraction.
Alpha-adrenergic vasoconstriction continued to restrict oxygen delivery during coronary stenosis without inducing net myocardial lactate production.

Structured PICO

Does alpha receptor blockade with phenoxybenzamine prevent sympathetic alpha receptor-mediated coronary vasoconstriction during norepinephrine infusion in dogs with coronary stenosis?

Population

Closed-chest dogs with left coronary artery cannulated and blood flow restricted by a moderate stenosis (70% area reduction)

Intervention

Intracoronary norepinephrine infusion following alpha receptor blockade with phenoxybenzamine (0.25 mg/kg, injected into the coronary artery)

Comparator

Intracoronary norepinephrine infusion with alpha receptors intact (before blockade)

Outcome

Myocardial oxygen and lactate extraction, coronary sinus blood oxygen tension, and coronary resistance at equal levels of myocardial oxygen consumptionsurrogate

Sympathetic alpha receptor-mediated coronary vasoconstriction operates even during coronary stenosis, limiting oxygen delivery and increasing myocardial oxygen extraction without causing net myocardial lactate production.

Cite This Study

Buffington et al. (1981) studied this question.

synapsesocial.com/papers/6a1a1397443d3ecd7cdf5331 https://doi.org/10.1161/01.res.48.3.416

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Implication

Alpha receptor blockade may attenuate coronary vasoconstriction during sympathetic activation with stenosis; leaves open relevance to human CAD.

Adrenergic coronary vasoconstriction in the presence of coronary stenosis in the dog.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Adrenergic coronary vasoconstriction in the presence of coronary stenosis in the dog.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider