Key result
Propranolol reduces norepinephrine clearance ~25% without changing spillover, showing no reflex sympathetic increase.
Why the study?
It was unclear whether a reflex increase in sympathetic nervous system activity contributes to maintenance of blood pressure during acute beta-adrenergic blockade with propranolol.
Does propranolol infusion alter norepinephrine spillover and clearance to maintain blood pressure in normal subjects?
Comparison
Propranolol infusion vs control period
Design
Physiological study measuring norepinephrine kinetics during propranolol infusion
Follow-up
90 minutes
Authors
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Explains plasma norepinephrine rise during acute beta-blockade as clearance reduction; hypothesis-generating for sympathetic tone assessment in clinical research.
Does propranolol infusion alter norepinephrine spillover and clearance to maintain blood pressure in normal subjects?
Absolute Event Rate: 1.42% vs 1.9%
p-value: p=<0.001
The rise in plasma norepinephrine during acute beta-blockade with propranolol is due to reduced clearance rather than a reflex increase in sympathetic nervous system activity.
Best et al. (1985) studied Healthy volunteers (n=16). Propranolol vs. Baseline / Control subjects was evaluated on Norepinephrine clearance (p=<0.001). Propranolol infusion reduced norepinephrine clearance from 1.90 to 1.42 l/min (P<0.001) without changing norepinephrine spillover, indicating no reflex increase in sympathetic vasoconstrictor tone.
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