Key result
Left sympathetic nerve stimulation after adrenergic beta blockade with propranolol caused a 32.9% decrease in coronary blood flow, demonstrating direct sympathetic coronary vasoconstriction.
Why the study?
Does sympathetic nerve stimulation cause coronary vasoconstriction after adrenergic beta blockade?
Does sympathetic nerve stimulation cause coronary vasoconstriction after adrenergic beta blockade?
Absolute Event Rate: -32.9% vs 35.1%
Sympathetic nerve stimulation induces coronary vasoconstriction mediated by alpha-adrenergic receptors when beta-adrenergic receptors are blocked.
Hypothesis-generating for alpha-mediated coronary vasoconstriction during beta blockade; human studies required before clinical relevance.
Sympathetic control of the coronary circulation was studied by eliminating the inotropic and chronotropic effects of sympathetic stimulation with adrenergic beta blockade. A remarkable vasoconstrictor effect of the left sympathetic nerve stimulation was observed after an intracoronary injection of propranolol, while the effect of the right sympathetic nerve stimulation was less prominent. The late increase in coronary flow after the cessation of the stimulation was observed to a lesser extent after the adrenergic beta blockade, while the blood pressure and heart rate remained unchanged. The sympathetic coronary vasoconstriction was almost abolished by adrenergic alpha blockade.
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Kuramoto et al. (1967) studied Healthy (experimental animal model) (n=13). Left sympathetic nerve stimulation after propranolol vs. Left sympathetic nerve stimulation without propranolol was evaluated on Change in coronary blood flow during the second phase (5-10 seconds) of stimulation. Left sympathetic nerve stimulation after adrenergic beta blockade with propranolol caused a 32.9% decrease in coronary blood flow, demonstrating direct sympathetic coronary vasoconstriction.
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