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Calcium currents in diseased human cardiac cells
Journal of Cardiovascular Pharmacology
|February 1, 1995
Summary
Human heart cells from cardiac transplant patients show altered calcium channel function compared to surgery patients. This suggests changes in beta-adrenergic and serotoninergic signaling pathways in cardiomyopathic hearts.
Area of Science:
- Cardiology
- Molecular Cardiology
- Electrophysiology
Background:
- Human cardiomyocytes from cardiac surgery (CS) and cardiac transplant (CT) patients were studied.
- L-type calcium currents were investigated in atrial and ventricular myocytes.
Purpose of the Study:
- To compare electrophysiologic and pharmacological properties of L-type calcium currents between CS and CT human cardiomyocytes.
- To investigate alterations in calcium channel function and signaling pathways in cardiomyopathic hearts.
Main Methods:
- Whole-cell voltage clamp technique was used to record L-type calcium currents.
- Cardiomyocytes were isolated from human atrial and ventricular tissues.
Main Results:
- Cells from CT patients exhibited larger capacitance and lower current density compared to CS patients.
- Isoprenaline (Iso) increased calcium current in both cell types, while 5-HT4 enhanced it only in atrial cells.
- While agonist affinity was unchanged, the response amplitude to Iso and 5-HT was altered in CT cells, indicating impaired cyclic AMP pathway potentiation.
Conclusions:
- Electrophysiologic and pharmacological properties of calcium current are altered in human cardiomyopathic hearts.
- These alterations include a reduced number of functional L-type calcium channels and diminished responses to beta-adrenergic and serotoninergic agonists.