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Receptor-controlled calcium discharge in frog heart cells.
1Department of Physiology, University College London.
Quarterly Journal of Experimental Physiology (Cambridge, England)
|December 1, 1989
Summary
Adenosine triphosphate (ATP) and alpha-adrenaline receptors significantly enhance calcium release from the sarcoplasmic reticulum in frog heart cells. This effect, crucial for cardiac function, appears independent of calcium-induced calcium release.
Area of Science:
- Cardiology
- Cell Physiology
- Pharmacology
Background:
- Previous research explored ATP (P2-purinergic) and alpha-adrenaline receptor effects on sarcoplasmic reticulum (SR) activity in frog heart atrial cells.
- The sarcoplasmic reticulum plays a critical role in regulating intracellular calcium levels essential for cardiac muscle contraction.
Purpose of the Study:
- To investigate the facilitatory effects of ATP and alpha-adrenaline receptors on SR calcium discharge in frog atrial cells.
- To elucidate the mechanism underlying ATP-mediated facilitation of calcium release.
Main Methods:
- Experiments were conducted on single atrial trabeculae isolated from frog hearts.
- Measurements involved assessing SR calcium discharge induced by action potentials under varying conditions.
Main Results:
- Both ATP and alpha-adrenaline receptors were found to facilitate action potential-induced SR calcium discharge.
- High doses of ATP (≥2 microM) increased SR calcium discharge approximately 14-fold.
- The facilitatory process appears largely independent of calcium-induced calcium release, as suggested by experiments with varying extracellular calcium concentrations.
Conclusions:
- ATP and alpha-adrenaline receptors play a significant facilitatory role in SR calcium release in frog atrial cells.
- The mechanism of ATP-induced facilitation may not primarily involve calcium-induced calcium release.
- Further investigation into the precise molecular mechanisms is warranted.