What is the clinical evidence from this study?

Intervention: CGS-21680 (A2aR agonist) vs. Isoproterenol. Primary outcome: Increase in Ca2+ transients.

What question did this study set out to answer?

This study investigates how adenosine A2a receptor activation affects myocyte contractility and intracellular calcium levels.

May 1, 1999AJP Heart and Circulatory Physiology

Adenosine A2a-receptor activation enhances cardiomyocyte shortening via Ca²⁺-independent and -dependent mechanisms

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Key result

Adenosine A2a receptor stimulation increased myocyte shortening by 54% with only an 8% increase in Ca2+ transients, suggesting predominantly Ca2+-independent inotropic mechanisms.

Population

Isolated, contracting rat ventricular myocytes

Comparison

Adenosine A2a receptor agonist CGS-21680 or… vs Beta-adrenergic receptor agonist isoproterenol

Design

Preclinical

Authors

AWAngela J. WoodiwissUniversity of the Witwatersrand THThomas W. HoneymanUlsan College RFRichard A. FentonBoston University

Discussion

Member takes

Implication

A2aR stimulation may enhance myocyte contractility via Ca2+-independent mechanisms in rats; leaves open translation to human HF therapies.

Key Points

This study investigates how adenosine A2a receptor activation affects myocyte contractility and intracellular calcium levels.
Isolated rat ventricular myocytes were analyzed using fura 2-AM for calcium imaging.
Myocytes were treated with A2aR agonist CGS-21680 and compared to beta-adrenergic agonist isoproterenol.
Inhibitory G protein pathways were manipulated using pertussis toxin and adenosine A1 receptor antagonist DPCPX.
A2aR activation increased myocyte shortening by 54% with a negligible increase in calcium transients (8%).
Isoproterenol increased calcium transients by 104% and myocyte shortening by 61%.
A2aR effects were primarily Ca2+-independent, as indicated by minimal calcium transient changes compared to beta-adrenergic stimulation.

Structured PICO

Population

Isolated, contracting rat ventricular myocytes used to investigate the effects of A2aR stimulation on contractility and Ca2+ transients.

Intervention

Adenosine A2a receptor (A2aR) agonist CGS-21680 (10^-4 M) or Adenosine (Ado) with/without pertussis toxin (PTx) or DPCPX

Comparator

Beta-adrenergic receptor agonist isoproterenol (2 x 10^-7 M)

Outcome

Myocyte shortening and amplitude of intracellular Ca2+ transientssurrogate

Main Result

Absolute Event Rate: 8% vs 104%

A2aR-induced contractile effects in rat ventricular myocytes are mediated predominantly by Ca2+-independent inotropic mechanisms, unlike beta-adrenergic stimulation.

Cite This Study

Woodiwiss et al. (1999) studied this question. CGS-21680 (A2aR agonist) vs. Isoproterenol was evaluated on Increase in Ca2+ transients. Adenosine A2a receptor stimulation increased myocyte shortening by 54% with only an 8% increase in Ca2+ transients, suggesting predominantly Ca2+-independent inotropic mechanisms.

synapsesocial.com/papers/6a23079f6e4b7ecdd5f73b00 https://doi.org/10.1152/ajpheart.1999.276.5.h1434

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Implication

A2aR stimulation may enhance myocyte contractility via Ca2+-independent mechanisms in rats; leaves open translation to human HF therapies.

Adenosine A2a-receptor activation enhances cardiomyocyte shortening via Ca²⁺-independent and -dependent mechanisms

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

Adenosine A2a-receptor activation enhances cardiomyocyte shortening via Ca²⁺-independent and -dependent mechanisms

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

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Also Consider