Key result
Sequential alpha 2 antagonism impairs endocardial and augments epicardial blood flow, indicating mainly epicardial vasoconstriction.
Why the study?
Does sequential alpha 1 and alpha 2 adrenergic antagonism alter regional myocardial blood flow in hypoperfused cat left ventricle?
Population
9 pentobarbitone anaesthetised open chest cats with left coronary artery hypoperfusion
Comparison
Sequential selective postjunctional alpha 1 and… vs Baseline hypoperfusion state
Design
Preclinical
Authors
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Should not alter adrenergic blockade in clinical hypoperfusion; leaves open translation of epicardial alpha 2 vasoconstriction from feline models.
Does sequential alpha 1 and alpha 2 adrenergic antagonism alter regional myocardial blood flow in hypoperfused cat left ventricle?
Coronary alpha adrenergic vasoconstriction in hypoperfused myocardium is mainly epicardial and mediated by postjunctional alpha 2 receptors, which counteracts endocardial hypoperfusion.
Westby et al. (1992) studied Hypoperfused myocardium (n=9). Sequential selective postjunctional alpha 1 (doxazosin) and alpha 2 (SK&F 104078) adrenergic antagonism vs. Baseline hypoperfusion was evaluated on Regional myocardial blood flow and coronary vascular resistance. Sequential alpha 2 adrenergic antagonism impaired endocardial blood flow and augmented epicardial blood flow, indicating coronary alpha adrenergic vasoconstriction is mainly epicardial.
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