What question did this study set out to answer?

To determine whether human cardiac tissue possesses spare beta-adrenoceptors for catecholamine-mediated positive inotropic responses compared to rat cardiac tissue.

February 1, 1992Journal of Cardiovascular Pharmacology

Spare Receptors for β-Adrenoceptor-Mediated Positive Inotropic Effects of Catecholamines in the Human Heart

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Authors

LBL. BrownUniversity of Leeds NDN.M. DeightonKyoto University SBS BalsUniversity of Duisburg-Essen

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Implication

In vitro study demonstrates limited beta-adrenoceptor reserve in failing human myocardium, indicating vulnerability to early functional decline during heart failure progression.

Key Points

To determine whether human cardiac tissue possesses spare beta-adrenoceptors for catecholamine-mediated positive inotropic responses compared to rat cardiac tissue.
Assessed beta-adrenoceptor affinity using (-)-[125I]iodocyanopindolol radioligand binding and contractile potency (pD2) for isoprenaline, adrenaline, and noradrenaline in human right atria and left papillary muscles across varying heart failure severities.
Constructed receptor occupancy versus contractile response curves under identical experimental conditions and compared human tissues directly to rat left atria and papillary muscles.
Rat myocardium demonstrated a substantial receptor reserve, achieving 50% maximal contractile response with only 1% to 3% beta-adrenoceptor occupancy.
Human myocardium possessed a markedly smaller receptor reserve, requiring 8% to 10% receptor occupancy in right atria and 20% to 25% in left papillary muscles for 50% maximal response.
Receptor reserve progressively diminished with worsening heart failure, culminating in a 1:1 occupancy-to-response ratio in end-stage disease (NYHA class IV).

Cite This Study

Brown et al. (1992) studied this question.

synapsesocial.com/papers/6a8a4f113eb0001306cbea36 https://doi.org/10.1097/00005344-199202000-00011

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Implication

In vitro study demonstrates limited beta-adrenoceptor reserve in failing human myocardium, indicating vulnerability to early functional decline during heart failure progression.

Spare Receptors for β-Adrenoceptor-Mediated Positive Inotropic Effects of Catecholamines in the Human Heart

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Implication

Key Points

Cite This Study

Spare Receptors for β-Adrenoceptor-Mediated Positive Inotropic Effects of Catecholamines in the Human Heart

Discussion

Member takes

Implication

Key Points

Cite This Study

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