What is the clinical evidence from this study?

Population: Cultured chick embryo ventricular cells. Intervention: Isoproterenol vs. Control (naive cells). Primary outcome: DHP binding sites (fmol/mg protein) (p=<0.03).

September 1, 1989Journal of Clinical InvestigationOpen Access

Coregulation of calcium channels and beta-adrenergic receptors in cultured chick embryo ventricular cells.

Q: What are the key findings of this study?

Exposure of cultured chick embryo ventricular cells to 1 μM isoproterenol for 4 hours reduced DHP binding sites from 113 to 73 fmol/mg and beta-adrenergic receptors from 44 to 17 fmol/mg.

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Key result

Exposure of cultured chick embryo ventricular cells to 1 μM isoproterenol for 4 hours reduced DHP binding sites from 113 to 73 fmol/mg and beta-adrenergic receptors from 44 to 17 fmol/mg.

Structured PICO

Population

In vitro study using primary monolayer cultures of spontaneously contracting chick embryo ventricular cells to examine the coregulation of calcium channels and beta-adrenergic receptors.

Intervention

Exposure to 1 microM isoproterenol for 4 hours, non-receptor-dependent activation of protein kinase A, or exposure to diltiazem for 18-24 hours

Comparator

Control conditions

Outcome

Abundance of functional Ca channels (estimated by DHP binding), beta-adrenergic receptor number, 45Ca uptake, and contractile response to (+)BAYk 8644surrogate

Main Result

Absolute Event Rate: 73% vs 113%

p-value: p=<0.03

Elevation of cAMP in myocytes is associated with a time-dependent decline in calcium channel abundance and related physiological responses.

Limitations

In vitro model using chick embryo cells may not fully represent adult mammalian or human cardiac physiology.
Determination of DHP binding sites as a marker for calcium channels has limitations, such as potential effects of membrane potential alterations.
The basal number of Ca channels displayed some drift during the course of the studies due to different batches of serum and embryos.
The exact mechanism of channel disappearance (e.g., sustained phosphorylation leading to internalization) remains to be fully confirmed.

Authors

JMJames D. MarshBrooke Army Medical Center

Discussion

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Implication

Prolonged beta-stimulation may downregulate myocyte calcium channels; leaves open relevance to human heart failure.

Cite This Study

James D. Marsh (1989) studied Cultured chick embryo ventricular cells. Isoproterenol vs. Control (naive cells) was evaluated on DHP binding sites (fmol/mg protein) (p=<0.03). Exposure of cultured chick embryo ventricular cells to 1 μM isoproterenol for 4 hours reduced DHP binding sites from 113 to 73 fmol/mg and beta-adrenergic receptors from 44 to 17 fmol/mg.

synapsesocial.com/papers/6a5c05f0f04bf07559368596 https://doi.org/10.1172/jci114241

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Coregulation of calcium channels and beta-adrenergic receptors in cultured chick embryo ventricular cells.

Structured PICO

Main Result

Limitations

Discussion

Implication

Cite This Study

Coregulation of calcium channels and beta-adrenergic receptors in cultured chick embryo ventricular cells.

Structured PICO

Main Result

Limitations

Discussion

Implication

Cite This Study

Also Consider

Also Consider