Antihypertensive action of propranolol in man: lack of evidence for a neural depressive effect

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Published on: December 18, 2014

M Guazzi, C Fiorentini, A Polese

    Clinical Pharmacology and Therapeutics
    |September 1, 1976
    PubMed

    Insights

    Propranolol, a beta blocker, reduces blood pressure by affecting beta-receptor-mediated responses. This study found no evidence of neural depressive actions beyond its known beta-blocking effects in hypertensive patients.

    Area of Science:

    • Cardiology
    • Pharmacology
    • Neuroscience

    Background:

    • Beta blockers are widely used for hypertension.
    • Their antihypertensive effects may involve neural mechanisms.
    • This study investigated propranolol's effects on circulatory responses.

    Purpose of the Study:

    • To test the hypothesis that neural depressive action contributes to beta blockers' antihypertensive effects.
    • To differentiate beta-receptor-mediated effects from other influences.

    Main Methods:

    • 14 essential hypertensive male patients were studied.
    • Circulatory responses to mental arithmetic (beta-mediated) and cold (alpha-mediated) were assessed.
    • Propranolol (320 mg/day for 3 wk) was administered.

    Main Results:

    • Propranolol reduced baseline blood pressure.
    • Reactions to stimuli were not altered in timing.
    • The pressor effect of arithmetic decreased, proportional to cardiac output reduction.
    • Blood pressure during cold stimulus increased via augmented vascular resistance.

    Conclusions:

    • Propranolol's effects are limited to beta-receptor-mediated circulatory responses.
    • No evidence supports a neural depressive action beyond beta blockade.
    • Findings clarify propranolol's mechanism in essential hypertension.

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